Incorrectly supp**** goods 3 times

On the 22nd of September 2015 i bought a Corsa D Complete lockset for R4550, the mechanic discovered that the transponder cable was missing and had to collect it from the spares, they gave me the cable but when they connected the ECU was not communicating with the clock meaning these parts were taken from 2 different cars. Went to take it back and after 2 days they gave me a complete lock set but this times it was not the part i requested. i took it back which they gave me horrible attitude & they gave me another ECU which was not complete & i refused to take it back and requested a refund since cannot deliver the goods. They refused with the refund & now they say i must bring the sample of my car's complete lock set so the driver can find the proper one. Right now i need my refund of R4550 and they are not taking it. I'm so frustrated & i would not recommend anyone to German Spares West as the staff is rude and are amateurs in selling spares. This has been going on for 3 weeks yet i did supply them with the right information from the beginning of the purchase. The best way is for them to refund me and which is possibly because the new invoice is from the 14th of October 2015.