Practical Car Rental, Red Robin, Frontier, Other Names Daily charge for not buying their insurance Ripoff Stockley, Heathrow United Kingdom

As always, I planned to use my Platinum US credit card to cover insurances on a visit to the UK. Because of prior good pricing and vehicles, I again rented from Practical.
On check-in I showed the printout I carry of the coverage provided by Mastercard and the desk clerk agreed it more than covered the value of the vehicle. However, he insisted I still had to pay 4 pounds plus VAT for "not buying our insurance". Given that I had been traveling for 16 hours and wanted to get to where I was staying before dark, I wrote on the contract "Under duress" or similar and took the car. The clerk say the charges was "because we've had a few problems collecting from the credit card companies", but also said he would "ask his manager later". I have never been charged this way before or since at any other agency in several European cities.

The bill came through with the surcharge, adding over 25% to my original expectation. I complained to Bank of America (which 'owns' my Mastercard) that I was being charged for something I did not want and for which I received no benefit. I also felt it was a penalty for using my credit card and thus against Mastercard conditions. BofA rejected my claim.

I have also emailed the UK Office of Fair Trading, but have received no reply as yet.

I urge anyone booking a car in UK to check to see if this surcharge is expected. Practical has many trading names it seems, so watch for their name in the small print.

ex-pat Brit
Los Angeles, California
U.S.A.