Looking for some advice please...

I have a 12 reg Ford Fiesta 1.4 Titanium Automatic. I purchased the car in May 2013 and it suffers from an intermittent fault with the automatic transmission.

Basically, every now and again, the car struggles and then a 'Transmission Malfunction' error appears on the screen and the car becomes erratic. I have read someone describe the fault as being like a learner driver learning to drive a manual car (jumpy/jerky). When this happens, the car feels very unsafe and it makes me nervous about doing long journeys, so much so that my wife has just purchased a new car to do all long journeys in, so mine will be purely to/from work.

The car is under warranty until June 2015 so I really need to get this fixed prior to the warranty expiring otherwise I can see it costing me a lot of money.

The car has been back to the Ford dealer previously and they have been unable to diagnose the issue, however, I have it booked back into the Ford dealer for the beginning of November and I would like advise about how to insist that they keep the car until they can guarantee that the fault is fixed.

Is there someone at Ford that I can write to? If so, can anyone point me in the right direction?

I have tried googling the problem I'm having and most of the complaints seem to be in America, but it does prove that there is an issue there.

I am really not happy as I paid almost £10,000 for this car (as a used car) and it's just not good enough. I really would like some assurance from Ford that they will fix it under warranty.