How do I get a credit on my account refunded back to me after FOUR times of being told it would be? It's been 2 months...

Hi there, I’ve been trying to have an approximate $200 credit on my account refunded to me for the last 2 months. I’ve talked to multiple agents four separate times via the Xfinity chat support and not only have I gotten different answers each time, the supposed refund method has changed each time as well... First, it was going to be electronically refunded back to my card — didn’t happen. Second, I was supposed to get a check in the mail — nothing. Third, another ring-around and I’m told that their supervisor will for sure do it the next day and I would get an email confirmation — nothing. Fourth time, I was told it would be electronically refunded back to my card — nothing. This last time the woman I was talking to just stopped replying when I asked for her for a confirmation number. I'll have to call and demand to speak to a supervisor or something because this is ridiculous. My service was at my last rental and each time I’ve asked them to change my billing address and email to my current ones and they probably don’t because I have gotten no correspondence whatsoever.  I’m highly frustrated and disappointed. I was a customer for over 2 years and at this point I’m at an absolute LOSS for words. If someone can help me, that would be great.