Car hire scam charges

Zazacaspar

I have recently returned from Malaga, Spain where I hired a car via an internet booking with OK Mobility
( 1.7 * on Trustpilot) for the period 31/12/22 - 5/01/23. 
I had previously hired a car long term with this company without incident, hence I ignored the rating. 

After leaving the airport and travelling to my hotel a short distance from the airport I noticed that the clutch byte wasn’t as good as it should be, the car was drivable, but I decided I didn’t want the car to get any worse or to breakdown on me. I decided that I would take the car back to the airport the next day. I tried not to let it upset me or spoil my celebrations for New Years Eve but it was clearly in the back of my mind as I knew I had to drive back to the airport the next day New Years Day,  so my enjoyment was fa  limited. I was extremely angry and disappointed that this car had been released to me, knowing that 2 days out of a 5 day holiday would be consumed with dealings with this hire car company, as the airport collection and interaction with the representative was not a pleasant one. This really put a dampener on my NYE celebrations.

On New Years Day I called the customer service team for advice, and informed them I wasn’t happy with the mechanical state the car was in and I was going to return it and I wanted a replacement. My total mileage to and from the airport was maybe 50km.
I returned the car and was given a replacement, I was happy with the new car. 
I returned the replacement car on 5th January 2023 and the car underwent a thorough check out process and the assistant declared, no new damage, everything is ok. So I was expecting my holding deposit of £1000 on my Mastercard to be released imminently, only to discover on the 8th of January my card had been charged £914.02 by OK Mobility and another £1000 is still pending.
I called the UK customer service number as surely this was some kind of error, only to be told I was being charged for a new clutch !
I have no correspondence from them and no clear out line of the charge and no evidence to date, even after repeated requests. 

I have lived and driven a car in Spain for 12 years and have been driving in Spain and in Europe for 26 years. So I am very used to driving this type of car.
I have read on forums that hire car companies are charging Americans clutch costs as they deem them unable to drive a manual car.
Now with the pandemic and less Americans travelling, this hire car company is hitting Brits with this charge. 
After research, the company class it as gross negligence and it is not in anyway covered by any insurance and once you have left the country, how can you disprove this? 

Is there any advice or help you can offer me? 
I feel helpless and feel very stressed at the amount charged on my card.