Home internet service really sucks lately

We have the Nokia Gateway an it worked great for 7 mths we are now on day 4 with internet going down every 20 minutes still on the replacement router they sent yesterday. I stopped counting the multiple people I have been passed to with TMobile but this one tech support in "California " lied out right jus to get me off the phone, so I had to hang up an call back to get someone else. I would cancel my account if it were not for T-Mobile being the only tower nearby. I work remote so internet is vital. I feel for the people that work for T-Mobile. It's not the workers, it's the company that should be embarrassed for such a bad quality of service.