incopentent NTN technicians

I bought my phone on the 25/12/15 at Jet Festival mall few weeks later after buying the phone I realized that charging point was not working 12/01/16 took my phone for repairs at Allandale Midrand the technicians fail to do their job and claimed that my phone was water damaged and say I have no warrantee demanded that I pay R330 so that my phone can be realized same day took my phone to the street comer to be checked it was not water damaged it only had a slight fault at the charging point only took 2mints to be fixed. am requesting that MTN pay me back my money as to they didn't help at all