Never received promised refund/ balance sent to collections

I was promised a refund over a month ago, but I still haven’t received it.

I contacted Xfinity multiple times, and each time I was told the refund would be processed within a specific timeframe. None of those promises were fulfilled.

While I was waiting for the refund, the balance that should have been offset by the refund was sent to collections.

I need Xfinity to issue the promised refund and address the fact that the balance was sent to collections while I was waiting for a refund Xfinity had already promised.