Avoid Green Motion Car Rental, London Heathrow, at all cost!

I wish I could write this review without a single star!!! I have been using Rentalcars.com for several years and this is by far the worst experience ever! Please do not fall into the same trap as we have and avoid Green Motion Car Rentals at all cost!!! I booked and paid in full for two Estate vehicles in January 2019 for the period 20 August - 3 September 2019 (GBP400 and GBP555 respectively). At the time I made the booking, I did not have flights confirmed and selected an arbitrary 11:30 pickup on 20 August and 11:30 drop off on 3 September. When the flights were confirmed, I tried to change the time, but could not do so online and was advised to cancel the bookings and make new bookings. However, the size of vehicles we require were not available and I left the pick up time for 11:30. Our flight arrived at 11:15 at London Heathrow Terminal 4 and after having to go through Passport Control, Customs (we were travelling with rifle boxes for a shooting competition) and baggage claim, we were finally able to catch two different buses to Green Motion Car Rentals close to Terminal 1. During this time I tried to phone them, but could not get through. Well, imagine my surprise when we arrived around 13:00 just to be informed that my bookings were cancelled because we did not collect the cars within 1 hour from the time I stipulated on my booking! They "gracefully" provided us with two different vehicles, but at ADDITIONAL cost of GPB504 and GBP680 EXTRA. Security deposits were also charged at GBP1405 on both vehicles. We returned to South Africa on 3 September, but our flight left London Heathrow Terminal 4 at 09:00, but once again, we had to book in our rifles with Customs shortly after 06:00 already. The cars were returned to Green Motion Car Rental, but no-one was there to check the conditions of the vehicles. Yesterday, both security deposits on both cars were charged on the drivers' credit cards - one accompanying an email outlining damage to the car (to the exact amount of the security deposit - strange, isn't it) and the other without any email or confirmation, the money was just deducted. We acknowledge one scratch on one of the cars and are willing to pay for that, but we refuse to accept responsibility for the other damage. Green Motion Car Rental only opens at 08:00 in the morning and we left the vehicles in their parking lot in the same condition as we found them, except for the one scratch. These two vehicles' rent cost us GBP2309 and GBP2604 for these two weeks - that is rediculous and borders on ********! Too bad I didn't read these reviews before doing business with Green Motion Car Rentals, because I see a similar trend in the majority of the reviews! If I can advise anyone, STAY CLEAR OF GREEN MOTION CAR RENTALS - THEY ARE ********* AND ******* exploiting tourists in need of transport!!!