Bad service and customer complaint

I bought a cellphone from my local pep stores in mogwadi limpopo and the device is faulty, i went back to ask to replace the phone and get a new one. The personel was not very helpfull and while still talking to an employee she just walked away and went to another employee. The woman also told me that she does not know about the problem so they cannot replace the phone. This is unacceptable and not a way to treat a customer complaint.