Never receive the refund

In January of this year, I discovered that my credit card was charged $204.67 for Xfinity's mobile service, which I never subscribed to. I called your customer service four times in February, and each time I was told that the charge would be refunded to my Visa account within 3-5 days, but I have never received it. The last assurance was ten days ago, guaranteeing a refund within 5 days. I have completely lost patience. Your phone lines are incredibly difficult to get through, and each time, I have to explain the situation several times to your agents. This has wasted so much of my time and energy, yet it has been utterly useless and your promises have not been kept. If you do not issue an immediate refund, I will be forced to file a complaint.