FirstNet will double your bill

I signed up with firstnet after being hounded at the AT&T store. I went in to add an iPad for my son but they promised that my bill would be much less so I signed up. After my first bill I knew I made a big mistake in signing up. It literally doubled so now I had two bills one with AT&T and one with firstnet. I tried to cancel or get my bill worked out so they would honor what they originally promised but they refused.  I’ve worked at a hospital for 7 years on the medical floors. In January Firstnet called and said I wasn’t eligible for the healthcare worker program so I said great cancel me. I paid a large bill in January and AT&T sent me new SIM cards to move my devices back. I did and paid everything that was asked of me. Now 3 months later I get a bill from Firstnet for $455! I called and said I’m not with them anymore. Basically they said that bc THEY never canceled me and they never moved my services over to At&t like they said they would I still have a bill. I’m not paying this balance with Firstnet and will be contacting AT&T and if they can’t help me I will be switching providers. Unfortunate because I love my AT&T service but there’s no way. Morale of the story DO NOT SIGN UP WITH FIRST NET NO MATTER WHAT THEY PROMISE!