Petrol **** with Thrifty

I have used this company many times in the past, but no more. There is a **** going on with the petrol. Last time I filled up and drove straight to return the car. I was charged fuel plus handling. I disputed with no joy. The same thing happened on my recent trip and this time I checked with the guy filling the car and we agreed it was full. I drove the 1km to return the car and again I was charged for fuel plus handling. I complained and the company said they will not refund me. It's the last time I use this despicable company. Please beware!