That may be a problem, cheap and efficient don't seem to get on too well. Although I have not had to use them, yet, there is a company called Auto Warranty Direct also the company used by the local Lexus dealer, just had a look for their name but can't find it , but A.W.D. have a web site:- www.autowarrantydirect.co.uk
Have a look, you get what you pay for at the end of the day.