Dissapointing, unethical and unprofessional - 1st time renting with Yesaway and not good !

The car looked and presented well - however, there was an issue with the gears and it had difficulty accelerating which was dangerous when overtaking. As we did a lot of travelling this became very frustrating. If the car had been checked before delivery it would most definitely have been noticeable. The most frustrating and in my view unprofessional matter was the deposit. It was not returned to me upon return of the car in same condition as confirmed by staff. They then told me i had to wait 1-2 months for the deposit to be returned. I rented many times with Eurocar, Avis and Hertz and every time my deposit is returned immediately. Usually they simply zero out the original charge held as a deposit not an acutal charge to the car, similar as hotels do when you check in. However, the deposit has been charged directly to my Citibank card and i am not paying interest on that and as of today my deposit has not been returned. I am more than angry about this as it was not mentioned either when making the booking or when the deposit was taken at the counter. Can someone please explain this unethical practice & also please confirm my deposit is returned immediately - this is not acceptable.