Refuse to pay out warranty that I have paid for.

I took out a mechanical warranty when I bought my vehicle. The refuse that I can claim from the warrenty, as the previous owner did not service the vehicle at an accredited RMI garage. When we took out the plan, nobody from the company notified me that I won't be covered, as the owner I bought the vehicle from did not service the vehicle. They took my money, and I can't claim for anything. I have since paid over R20000 for problems to the vehicle. I feel this is not fair, as I have paid the money to get the warranty. Worst company to get a mechanical warranty from.