Third party claim gone wrong!

An outsurance client bumped into my car at the rear end in January. After weeks of going back and forth they finally decided to pay me out. They sent me the forms and everything and offered to pay me out the money of a quote they provided. I signed the papers and this morning when I called them to ask how long it will take for the money to reflect in my account so I can have my car fixed, the guy told me they made a mistake and that shouldn't have been the amount they are supposed to give me and that he was suppose to give me the amount of the cheapest quote available. So now if I want to use the quote and the guy they provided then I have to pay the outstanding amount out of my own pocket. They are seriously a bunch of ****** and they know exactly how to rip people off. I have to now pay thousands of rands extra if I want a decent job done on my car. This is why I will never take out insurance from outsurance but how do you prevent an outsurance client from bumping into you?