Billing problem representative unhelpful

Last month I had some issues were if you look at my bill it show late charges and also phone charges I did not authorise.I had to call at&t 3 months now for different issues and it's reflecting on my for about a hundred dollars and yesterday I had to put up wit someone that gave me a really bad attitude.I'm not happy with at&t at this point.So far every time I speak to a representative they tell me one thing but I'm not getting my results.