Bad service from Super Quick need help

Hi I'm from Cape Town and went on holiday in Knysna. I went to get a CV joint at Supa Quit Knysna in December and turns out they put on a wrong one by the time I got back home. I called them and they sent me to the Bellville branch however now they say they can't help me and referred me back to Knysna. Can you please help me with a solution I still have 6 months gaurentee left?