i used to sell them when i was a new and used sales executive at a main dealers, i would knock my pipe out selling the warrentys due to the kick back from the warrenty company and when the car broke down and the mug...... i mean customer came back and complained i would have to refer the mug to the warrenty company which was 250 miles away and reluctant to part with any cash for them.
the best warrentys are from the garage themselves,i sold them included in the deal with the good stuff that the boss knew was a good car and as there was say 2 grand profit in the car he knew if it did go bandit he could fix it and fook them off.