Bad service

I bought phone Sunday afternoon Mall of the north ..I was traveling back to Gauteng from Polokwane ..than I used the Monday on Tuesday I have noticed that this phone it's not working like sometimes there is no network and when some call it's freezing ok I thought maybe it's just for that day than ..one of my family called me on my husband phone told me that why your phone it's off mind you I have my phone and it's on I told her that my phone it's on .I switch the off and on than I realised that I have 6missed call ok I took the phone to sunnypark Ackrmens they told me the is nothing they can I assist me with I have to take it back where I bought the phone my frustration kick in mind I don't have I'm doing job hunting I started to asked my self about that missed calls I have received ok than I asked someone who was traveling back to limpopo on Saturday ok we went to to Mall of the north where I bought the phone when I got there I explained my problem to the cashier who called the lady by the name of pheladi ok I explained my problem to pheladi ok she asked me to step aside she will assist me I waited more than 30 minutes to get help ok pheladi came back she ask me my contact number she started to call my number ok the phone ring and she told me that she doesn't see any problem with the phone it's useless for to book a phone for repair while she tested the phone from her side and it's working .than I asked the lady to call headoffice instead of calling headoffice she told me that the phone it's on the charge ok after some few minutes again pheladi give me a phone to speak to some one by the name of Johanna who told me that she will able to assist me on Monday she will called me which she never did I'm so disappointed I have in me which it's not working and according to me seven day warranty it was not yet ended so I want my money back cause it's useless to have phone which I'm struggling to used it especially now cause I'm not working and I have spend all my phone to buy this phone and end up no using it