Promotion not honored after being a mobile line to Xfinity my credit is frozen and I wasn't er asked to unfreeze it

I brought a 2nd line to Xfinity after trying their free service for 6 months. I left Verizon after 31 years and I was told that I could get a $400 credit toward a new phone if I brought my mobile phone to them. The agent ran a soft credit check without telling me and said I'm not qualified. I said, how can that be? A week later I called back because I did not receive the SIM card in the mail that was promised to me. I told the next agent that I forgot that my credits Frozen I would have easily qualified for $400 phone. They said there's nothing that they can do because I already started the service and it's past that date to do this. I called all three credit companies because a supervisor Xfinity said I need to prove something in writing although she didn't send me an email and I have nowhere to send it to. Because of situations like this with Xfinity I have my credit Frozen and a lot of people do but we're being penalized for it because it was frozen if they had asked me if they could do a credit check I would have stated my credit's Frozen let me unfreeze it. Is there anything that can be done so that I can receive the $400 credit? Otherwise I'd prefer to go back to Verizon because they offered me an even cheaper plan than what I would be paying in another 6 months which is $40 for the first line and $20 for my second line at Xfinity.   I don't understand why the customer support has to be so severe and I've been on the phone for 40 hours in the last month and have kept detailed notes and yet they won't listen to a call from July 15th and it's now August 8th they said they can't listen to it and nobody seems to know why but that's when I was promised by the agent that they had a network extended which you do not have and that he would send me the SIM card and that wasn't done.  Why not bend to keep someone there and say will offer you the $400 credit towards a new phone and make me happy otherwise you've just upset me and I'm going to go right back to Verizon. I thought I would try using the chat to see if I could get a better answer from somebody. I left to use your Wi-Fi from astound and what I loved about Xfinity is you have a dedicated department for people with disabilities. Although when I have a trouble now nobody is able to assist me.