My cell keeps losing and droping service and Xfinity is not helping.

So I've heard of a few users with issues losing signal and their phones constantly going into SOS mode. Well now the issue just started happening with me 3 weeks ago. I can try putting it in airplane mode or restarting the phone and sometimes it will pickup service again but the signal is very weak and only last for a few minutes. I waited a week to see if the issue would resolve itself and nothing. I went to Xfinity mobile store where they did troubleshooting for over 2 hours, reset the phone and lost my data, multiple sim cards tried as well. The issue is still happening and they will not help me or give me a credit for the issue. I can't keep doing this because it is hurting my business so I just purchased another phone plan from another company in the mean time. The phone was purchased from Xfinity on a payment plan, with 11 months left. Xfinity told me they can't help me because I've had the phone too long. They sent me to Best Buy, Geek Squad were I had to wait another week to get an appointment. Geek Squad said the diagnostic on my phone came back that there is no issues with it.  I've called customer support to see if I can get a credit for this month service and they denied me. They said I need to do more troubleshooting. I don't have more time to waste, the tech at Xfinity store already was working with a level 3 tech, can't they see notes on this. I've been a long time Xfinity customer, but fairly new to Xfinity Mobile, and I'd like to say this is the worst mobile support and customer services I have even seen in 20 years.