Bad service

Good Day I bought the battery at Ulundi Battery Centre last month on the 16 June 2018 and the battery is dead it doesn't start. 21 days since i bought the battery i took it back to them and they said they will fix it and i must collect it the following day still the battery wasn't working properly. 23/07/18 Today i went to them they took the Battery they said the will take it to Head office to see whats the fault. am not happy the way the handily my issue Regards M.O Zondo