Xfinity refuses to issue my refund

Xfinity has been charging me for a phone line that was never active, a total of $480. In addition, for 2 years, I was overpaying $20 on my current line. Angel, the agent I spoke to on March 24th requested a refund from her financial team. I was promised a refund in full within ten business days. I would also receive an email and phone call a few days after the conversation with Angel but none of that ever happened. I have contacted support multiple times thereafter. On April 28th, Xfinity deposited $160 on my bank account but I never received the rest of my payment. And I never received a refund for my current line.