they cant repair phone and its under warranty

I bought a phone on the 28th November 2014 for a R1000 and the phone now is faulty its not charging I took the phone to the shop on the 29th April 2015 cause it is still under warranty they took it but to my surprise they called me on the 2nd of May 2015 to come and collect the phone cause they cant fix it, please help me I dont know what to do my contact is ***