Unacceptable Service /Upgrade to faulty equipment

Dear Reader <br> <br> I did an upgrade at your Vangate Mall Cape town Store on Monday 29 June 2015, the choice of mobile phone was M4 Aqua ( 1st time moving to a Sony product ), the phone went on for - 2 hours on Tuesday and died I then charged it fully and it went on for 8 hours and never went on again, also noticing the charger only fits half way in to the charging port, I asked other Sony users if this is correct they confirmed that it was not, I logged this call to the store manager Clinton ( he was very unfriendly ) Wednesday morning 1 July 2015 and due to me not getting to your store in time in the evening after work I returned the phone Thursday Morning as I had to take time off from work due to the inconvenience caused by Vodacom , I received no feedback, I was told they can not replace the phone even though I am within my 7 days and it is OBF they will send it back and it might take 2-3 days, I had to call the store this morning 3 July 2015 for feedback they couldn't give me any feedback and said they will get someone to call me. I would like to cancel my contract as I am within my 7 day cooling off period as per the consumer protection Act. <br> <br> kindly advise the way forward.