GoldCar Rental review: £50 cancellation fee

We set up the hire car on line with Goldcar but i unfortunately I put in a manual car instead of a automatic, when I realised this I tried to amend it but I was not able to change it so I had no option but to cancel and re did the hire agreement for the automatic car.  We were surprised that a charge of £50 was made.  I spoke to a gentleman in the hire company office he was going to deal with it, as I did not hear from him I emailed Goldcar, who just kept saying it was there procedure.   
All I wanted them todo is to look at the situation surrounding the cancellation which was minutes from the one car hire agreement to the other.

I await your reply regarding this matter.

Thanking you