Breach of contract, conditions, bad service

I bought a phone on the 4th February 2018 at pass 10 am at a pep cell as per normal told u have seven days to return if any fault with phone , on the 10th February 2018 around 6:30 to 6:45 pm attending a event the phone just switched off unexpectedly, thinking might be battery I tried to charge it when got home. After hour I realised nothing happening and put all stuff together. I returned to the store on 11th February 2018 with everything and explained story was told because is 8th day phone must be booked in and nothing can be done. I argue fact then of broke when store closed and middle of night why must I bear brunt and cost? Why then is call centre closed Fridays? Why is the no fault line to call? Why can't managers do anything over a weekend? I have logged this with store and area manager Sunday, call centre Monday and Tuesday as well as emails and still awaiting feedback, manager said Monday can't do swop as was 8 days? I will not accept that at is major breach of seven day rule and also of consumer act. I will also not accept the current service I am receiving since Sunday and will take all necessary steps to rectify this all I want is other brand phone or my money back. Why it taking 4 days of ignoring no answers but have a issue I came early Sunday morning on 8th day to return phone? So who was I suppose to contact at night on the 10th which was also my birthday. This is unacceptable on many levels from this store.