I have been bullied in my childhood, I know how much it sucks to feel like that.
I have lived in the US for 7 years, I believe to have a strong accent (I know because people always ask where I'm from. And there are some words I still have a hard time pronouncing, so I have to repeat them 3 times till people get what I'm saying). Of course I have noticed improvements - meaning fewer people asking. And most of the time I am not made aware of my accent by others.
I have worked in customer service at a gym, so not the most professional or typical setting of all, but definitely plenty of people interaction. I have never experienced severe harassment or bullying regarding my accent, especially not in a way that is interrupting or unprofessional.
I totally wonder why our experiences as immigrants are so vastly different. I am white, German accent, lived in Michigan, and recently moved to California. Always in suburban areas. And I mention this not only because I'm curious about the specifics or your situation, but mostly to see how it compares, and if any of those parameters might cause our situations to be so different.
The only thing I've noticed about people from the country is that they are often not used to hearing accents, and therefore have an even harder time understanding me. Though I can't imagine you'd be in the middle of nowhere.
I suppose you could move to an area that's more tolerant, but I can't imagine we'd have such a different experience because we live in a different regions of the US.
I hope that none of the unchangeable parameters have much to do with it, especially the part about being white...
My experience has been that people are (annoyingly) curious about my origins and love to share what their experiences with my former country are, or where their relatives live, and if it's anywhere near where I grew up. (The worst one is: "Have you been to this German restaurant in town yet?") While I am frustrated to have these conversations for the 100th time, I do see it positively - openness, curiosity, politeness - very unique to American culture. So I do, in a way, appreciate it.
From time to time there will be jokes about my accent. And I laugh at these, because they are funny! I like to hear people making an impression of my accent, it's hilarious! Often people are actually too shy to let me hear their imitation though, it takes some convincing...
And I can laugh at it, because the fact that I talk different from everybody else is comic and amusing. I don't appear out of place until I open my mouth. Because culturally I don't act different, I don't dress different. At least I like to think so, but it's tricky to have an accurate, objective picture of oneself.
So my questions for you to think about are:
- Is your self perception in check?
Is your accent really not as strong as you think?
Is it really 30% of the time that people make fun of you or does it happen for 10 minutes out of every work year (which has about 160,000 minutes. So 10 minutes of poking fun at you is like not even 1% - especially considering that the first 159,990 minutes were open, welcoming, friendly, and everything)
- Is your sense of humor in check?
Are they really being mean? Or is it really kind of funny? I don't recommend letting it slide, I recommend joining in the fun. Sometimes your accent might be the first and only thing on people's minds when they meet you, but they're too polite to say anything. If you break the ice in that manner (making a situational joke about having an accent or being a foreigner) it may be easier for both of you.
- Are you culturally integrated and assimilated?
I feel that my accent is only that: An accent to who I am. It doesn't completely describe me. I am American, I act American, I live and breathe 'murican. I have embraced and adopted the culture. So I think because of that I don't come across like I just got off the boat, in spite of my accent. How to integrate yourself culturally is a whole nother question to tackle, that's not actually as easy as it seems - especially if the countries appear to have similar cultures.
- Could it be a regional, or circumstantial problem?
I doubt this, but maybe you have to move. You can't turn white and you can't turn European. If I am being too ignorant of race here and it's an issue at play, I truly apologize. I can't offer any helpful advice if that's the actual problem. Which makes me feel bad for America :(
So, excluding racial issues, my solutions are all about changing yourself, changing your perceptions and changing your expectations.
Finally, to give you a palpable answer that you can take immediate action on:
When I first got here, I have used a program "Accent Reduction Made Easy" by Jane Wellborn. Great program with audio drills that can help you master the most difficult phonemes. I can really recommend this program, revisiting it even after 7 years is still helpful.
Edit 1:
I just re-read your post again. And the severity of which you describe it is baffling to me. As the currently most upvoted comment says: It's hard to believe that such a place exists.
I do feel badly for your experience, and clearly this is getting to you. And I'm sure it's hard.
But it does bring me back to self-perception, and generally perception, which can actually have cultural differences... What are they seeing and experiencing, what are you seeing and experiencing, what are both of you missing?
Edit 2:
The currently most downvoted answer is actually very important. Yes, bullying is bad, and yes telling you to just suck it up is bad. But there's more to it than that, and it's not easy, either. It comes down to self-confidence. Why are you worried about a joke during a presentation ruining your image and compromising your ability to do your job? What would a highschool teacher do every time this happened to them? Why are you worried about your "image" in the first place? Maybe, ultimately, you have to become aware of your own self worth and develop a healthier self confidence. I have my fair share of those issues to work on, too, so I know it's difficult. But not impossible! We are adaptable, and with enough practice you can master anything. Psychotherapy can probably help with this. I said "healthy" self confidence, because this is a mental health issue.