monthly credits not shown on bills

Hello, I have an extremely frustrating experience with respect to Xfinity billing. I have been trying to file an official complaint but there doesn’t seem to have a proper channel for me to do so. Hopefully you can help me resolve the issue once and for all.

I am an Xfinity internet/cable customer. In September, I placed an order to transfer two mobile phone lines to Xfinity Mobile.

During the live chat discussion with Xfinity Mobile regarding the transfer, your sales rep promised me that I would have $15 of MONTHLY credit to my Xfinity internet/cable. Based on the information he gave, I decided to effect the transfer. Unfortunately, the credit was nowhere to be found on my Sep, Oct and Nov bills.

I contacted your live chat team (in late October?). After being bounced back and forth between your mobile chat team and your internet chat team a number of times, finally somebody with your internet team tried to help me. She assured me that the $15 credit would be applied to my account to cover the Sep bill. Also, a code would be input to my account so that the credit would be there every month from then on. Given my experience with Xfinity, I was skeptical but there wasn’t much I could do at that time. I was disappointed to find that the credit wasn’t anywhere on my November bill. By the way, this particular chat took over two hours. 

I chatted with your agents again on Nov 16. I was bounced back and forth and back and forth many many times between your Mobile team and your Internet team. I had to talk to 12 agents and none of them could help. I was cut off when I was waiting for the 12th (or 13th?) agent and there wasn’t any solution. This chat lasted for over 3 hours. 

Kindly help resolve this issue PERMANENTLY. Many thanks.