Hi -- Without a doubt in my mind Warranty Direct, I had Two claims one was a new gearbox and they paid out no hassle, all they insist is the car is serviced as per manufactures schedule ..but this can be a garage of your choice not necessarily the dealers. Keep all records, they do ask to see them in the event of a claim. !
As always read the fine print to ascertain if it's right for you before purchase,15% off normal price online.
http://www.warrantydirect.co.uk/car-warranty.html