Space in vehicle good and made for comfortable travelling. Car dirty on pick up inside and out

The car was dirty on the outside and windows were very dirty with marks all over them . The body of the car was also marked and dirty. The inside was grubby and dirty and generally unkempt with rubbish still inside from last customer. I raised the concerns and was told two day rental would be discounted from my bill. I have emailed and been told that this was not possible as I’d prepaid,so was told money already taken in the form of additional drivers ! I am not clear how much this is in relation to two days of rental , I am not clear how this money was paid back to my account without a card or pin present, I would Like clarifyication