Pathetic Service

On the 1/03/2015 I bought a Nokia lumia at Markhams Langeberg mall, the lady who was assisting me told me that should the phone give me problems within 7 days of purchase they will exchange or give me cash back ,as soon as I got home I had problems with the phone ,I charged it untill it was full , but the battery wont even last 2hrs, on Tuesday the 03/03/15 I went back to the branch and inform the Manager of the problem she said she would keep the phone over night and check it, when I went back the next day she told me there was nothing wrong with the phone, I took the phone and it continued giving me problems ,Saturday the 07/03/15 I went back and told her I did not want the phone it was giving me problems, she told me they wont exchange nor give any cash back,the phone was fine and became very rude she went as far as calling me a **** I had to leave the phone again with her , I was shocked by her and attitude after all the years spending my hard earned money, that is paying her salary, at their store,