Useless Repair

I sen't my phone away for repairs. no one called me back to advise that my phone was ready for collection, i had to call out of my own, upon switching the phone on 1st this was not my own phone as the IMEI numbers diver 2nd the problem seemed to be solved, however now the phone does not read my sim card and PEP stores in Elsies river Halt Road is telling me i need to pay to fix it and this after one day after collecting it