Someone please correct me if I'm wrong, but Mint Mobile runs on T-Mobile network.
And in my short lived experience many years ago, T-mobile was terrible. I had switched from Verizon to T-mobile to try to save some money and had all the same experiences as you and more. I was still within a 2 week window that I could cancel my contract and return my phone and get all my money back so I did...and went back to Verizon.
Verizon isn't necessarily mustachian but it's one thing I refuse to compromise on. We travel a lot of places that a verizon network is the only one around...my family's sprint phones are even useless.
Based on your post, they haven't gotten any better so my only advice would be to dump them and switch to another provider.