TalkTalk oops

Every three months, TalkTalk bills me a couple of thousand pounds for my ethernet link. This month they billed me. And then they billed me again.

We noticed this on the bank statement, so we called them. We got the usual runaround "not my department, try elsewhere" but eventaully, they admitted that yes, they double charged us. A "computer error", apparently.

"Why didn't you tell us you double charged?"
"We've done a refund."
"So you knew you'd double charged. Why didn't you tell us?"
"."
"And why didn't you tell us you'd done a refund?"
"."
"How many other people have you done this to?"
"Some."
"Do you know what happens when you take a couple of thousand pounds out of the bank account of a small business that they weren't expecting to be taken?"
"."

So I've asked them what they plan to do about compensation.