Extremely poor, dishonest service

I bought a cellphone in totalsports east rand mall on Saturday, 15/ 9/2018 for my mother. Upon using the phone on the evening of the 15/09/2019 we realized that it gives a problem when I pick up calls. My mother went to Totalsports Volksrust on Monday 17/09/18 where she was told that they see no fault. The phone continues giving the same problem and was taken back to Volksrust totalsports on Friday where I was rudely told that the phone must be taken for repairs despite the fact that it was within 7 days which in my understanding it is an out of box failure. I called headoffice and the person that I spoke to said every store has their own policies. I bought at the store because I assumed I would be buying from an honest company who does things as per whats written down. I will never buy from that store again. To top it all off they took the phone but not the paperwork now my mother must go back to the store again which is an expense on her. PS I went to the store I bought the phone from and was told that the phone will be exchanged because it was within 7 days.