I was an IT guy at my previous company, but I left an year ago because I found another IT job with more pay. The previous owner calls me to see if I can do part-time because the only IT guy they had left, and also because I setup everything when I was employed there. I agreed to help out, but didn't discuss my hourly rate (my fault I guess), but I'm still being paid the same hourly rate as when I left an year ago. When the owner called me originally about coming back as part-time he said I would only be doing task 'x', but now he's asking me about more things (because I was the one that setup the network, and the IT guy that left didn't know anything).
How can I tell the owner I need a raise if I'm going to be doing more work than we agreed on. I still have my full time job plus this part-time job.
Also, the owner hired me back plus another IT guy, but this new IT guy have literally 0 IT experience (this is his first IT job), and every time he does something he keeps bugging me for help even if the owner agreed that I'm only supposed to do task x. I helped out a few times since he's new but I don't think I owe him to help out every single time.
My question is, how do I ask for a raise? I've asked the owner via email couple of times, but he never responds to that. He only emails when he needs my help with IT related work. IT related work he said I won't be doing.