released money

Ive been renting a car from Avis. I use my cheque debit card Money get put on hold everytime and on return of the vehicle. Avislift the hold and contacted fnb. Just to find out only 1 transaction was lifted and the others was apparently also lifted by 2 different ladies. The bank manager spoke to debitcard and then we had to hold on for an hour and 5 min but the lady came back and confirmed that only 1 amount was released. She reconsiled the account. But Fnb blames Avis and ive got documentatio. From Avis that they lifted the hold. Its a huge amount of my money that fnb is sitting with and after 30 years with Absa and 1 year with Fnb im thinking of moving back to Absa.