Rental Deposit / Tyre & Windscreen cover

I have recently had a vehicle from First Car Rental, due to my personal vehicle being involved an accident my insurance rented me one from First Car Rental. I thought that I would only have the vehicle for a week as my car didn't have a bad knock, so I included the tyre and windscreen cover. On the 9th day of the rental and being informed by my insurer that the assessor still haven't been to my vehicle. I contacted First car to remove the tyre and windscreen cover, as it was going to be and expensive exercise and I was informed that it was removed and all is in order. After the rental, I received the rental invoice and I have been charged for the duration of the rental for tyre and windscreen cover and only informed now that it can't be removed once accepted, otherwise that rental contact had to be cancelled and a new rental contract be done. I did my due diligence to call and cancel with the staff (Eugene) and he confirmed with his manager (Mr. Ranken) that it was removed and he(Eugene) said that I will only be billed for 9 days. Why was I not informed when I phoned on the 23rd April 2025, that I should cancel the rental contract and do a new contract?