Avis Misleading Staff

Booked a car online on 20 March for 21 March 2018, on the 21st I cancelled my booking via Avis call centre and went to their East London airport branch. The Avis East London branch said they can’t cancel the booking I must call the call centre the following day as it was a holiday on the 21st. I called on the 22nd an I was put on hold until I ran out of airtime. I sent an email to the head office on the 22nd, the response was the staff misled me as the booking wasn’t cancelled. Who’s at fault? They still don’t want to refund me.