Credit card division poor service

On the 29th January 2019, i paid a deposit via my credit card to Avis car rental. Upon calling them to find out when the deposit will be refunded i was told that they have already released the funds and i need to check with the bank, I called the bank on 3 occassions, twice holding on for over 15 minutes until i ran out of airtime. On the third attempt i was lucky after 8 minutes!!! The consultant is not able to tell me if i was refunded the money back. According to Avis they have released the funds. Please can someone just tell me if this has been released back into my account by doing a recon. I do not understand how Avis is able to "block" out the deposit on my credit card & now its almost impossible for anyone to tell me if the funds have been "returned" or "unblocked". I cannot see this on my statement.