I was incorrectly billed $100 for internal wiring but xfinity refuses to refund it.

My internet has been constantly going out. When the technician came out, they replaced the outside grounding wire but incorrectly billed it as a internal wiring code. Because of this xfinity charged me a $100 service charge. I tried to dispute it but they kept saying because the technician coded it as internal wiring then they wont refund me. Even after that my internet was not working, another technician came out and fixed it by replacing the outdoor line to my house. He even added comments in his notes saying that I should not have been charged the service fee for the last as it was outdoor wiring.

I cant get ahold of any live person to help with this and I was even promised it would be refunded by a agent via chat but I still have no refund.