Fail to return injectors from service guarantee

Hie i have a problem with the owner of Mike's diesel fuel injection pumps and injectors .i got injectors from him on service exchange for a price of 4500 on fitting his injectors they failed and i send them back to him as he had given me guarantee of 6 months .now after sending them back to him he is now ducking and diving to send them back to me giving an excuse that he is busy . His name is Michael *** my contact no is ***