Always called into work/ job burn out

I've been working restaurant jobs since I was 17. I'm 23 now.

I get called in on my days off all the time--workers have other plans, someone doesn't show up, or something else always comes up. Although I hate it, I usually say yes because I really need the extra hours. There've been a few times where I just say no because I don't feel like working--but most of the time I don't have anything stopping me from working, so I feel like I have to.

I know I'm really not obligated to cover for other people, but I am always the one doing it. Is it like this for anyone else?

My father works a more professional job as a manager, but on his days off, the phone is always ringing. He doesn't get a break. I don't know how he puts up with it. Is it like this for any of you, who don't get called in, but are constantly bothered?

It used to not be a problem. I'd be happy to go in and get as many hours as possible--the shifts are pretty short anyway. However, I've been at this job for three years and am really tired of it. It's very repetitive.

Oh well, less than three months left at this place. I'll just grin and bear it.

Anyone else feel like complaining about work?