Last summer I had an internship at a local tech company doing software development. I felt like I did a pretty good job and was consistently told by my boss and team that they enjoyed my being there and were very happy with the work I was doing. My boss's supervisor even went so far as to give me a fairly sizable bonus near the end of the internship as a thank you. At the end of the internship I was told by my boss and his supervisor that I was more than welcome to return to intern again next summer and to let them know as the summertime got closer.
This year I looked at some other companies internship programs but nothing ended up really fitting so I decided to take my boss up on his offer and return to intern again. At first I emailed my HR rep, explained the offer that was given to me and asked how to proceed/when things needed to be done by. The email was read about a day after I sent it (I have a mail tracking program) but I never received a response. I waited about two weeks and finally decided to email my former boss about it directly. The email was read 20 minutes after I sent it but once again I received no response.
It's been 4 days since my last email and I'm confused as to how to move forward with this. Do I email my former boss and/or HR rep again politely reminding them of my previous email and asking for a response, or do I wait? It's getting pretty close to the time where I received my offer as a first time hire and I'd rather not lose my spot because they have already hired new interns.