I had the opposite experience with BE when I left the UK. I found out there the account wasn’t cancelled properly and there was an outstanding debt on the account.

I emailed, then they replied and admitted fault, apologised, and refunded me. No sitting in phone queues, no treating me like a criminal.

Unfortunately looks like they got bought and shut down. https://en.wikipedia.org/wiki/Be_Un_Limited

Seems like the good guys lose in this business.