Did you call them using your phone, or with a phone in the room?

Reason I ask is that many hotels record calls, and if you phoned the desk on your phone, then the call has definitely been recorded, in addition to having the call log on your phone. If it's the room phone, then I'm not sure if these are recorded.

I'm unsure because I've only ever worked in budget hotels that a) didn't have phones in the rooms, and b) never recorded phone calls.

You could try disputing the charge with your bank/credit card company, and if that fails, I imagine you'd have to take it to a civil court - but then you got to factor in if the cost is even worth it.

Good luck!