Still waiting for my refund after 2 weeks!

I bought a second hand engine from Quantro Auto Spares on condition that I can return it if I was not satisfied.<br> Needless to say that I wasn't. After returning the motor on the same day as receiving it, they refused to refund me and said that they would repair the engine instead. I received a letter from them that stated that they will repair the engine and that I will receive a 3 month guarantee on the engine. After 7 working days, I phoned them to find out when I could collect the engine. I was told that they would rather refund me the money as they did not want to do a \patch job"on the engine"