Final update.... The issue has now been resolved.
I have the car back and it appears to be fully repaired. The replaced part was the air conditioning evaporator core. It took them 5 weeks to carry out the repair, and when the technician finally got to the evaporator, it was covered in white corrosion.
My lesson from this, if you buy a car and suspect a serious fault, get it looked at or return it within 30 days of purchase. Also, don't get fobbed off. I have been complaining about the
problem since September, and it only got fixed in December.
The first garage I took it to refused to fix it, and told me I could be liable for costs in the £1000's. The second garage had it for 2 weeks, said they checked the evaporator, and there was no fault found. They also broke my door handle. The third garage have somewhat restored my faith in Seat. They collected the car, gave me an almost new
Formentor courtesy car, and fixed the evaporator fault and the door handle. They also dropped my car off and took away the
Formentor.
So in 5 months of ownership, I didn't have the car for a total of 7 weeks. 1 dealer refused to fix it, 1 lied to my face. I have had to battle to have it fixed, been told it couldn't possibly be the evaporator, must be skin flakes or the a/c cleaner I used etc. Many emails and phone calls I made got no reply or call back. For my troubles, I have been given a £300 voucher I can spend on Seat accessories.
Will I purchase another Seat? Probably not. Which is a shame as I was already pricing up
Cupra Ateca's when this started. I plan to keep this
Ateca for a while, but I will never be taking it to a Seat garage for work. And if it ever needs warranty work again, my local dealer was the first to turn me away!