Terrible internet

Ive had at&t for years now and it started off great and even when i did have a problem i didnt mind because of how fast it was and great service. But for the last year or two it has absolutely went down hill to the point im considering finding another provider because half the time out of the week it isnt working, it is super slow to where i cant even load a page on my phone much less game on my xbox with my friends. I find it ridiculous to pay this much money for something that doesnt work not to mention years ago when i signed up they told me it was unlimited and now i keep getting charged for going over a certain gb of my usage which has never been a problem since this past year and nothing has changed as far as how much i use it. It is probably from taking so much longer to do stuff on the internet now. Back to my point though i need some serious help before i find somewhere else i have people with off the wall providers that do better than my internet.