Refusal to terminate contract despite informing me of incorrect specification

Very disappointed in MTN. I have been a loyal contract customer for over 15 years. On 10 October, I went to MTN Mega Store in Cape Gate for a new contract for my daughter. We enquired about two handsets (Huawei P9 and LG Q60) and were told both had 64GB Storage according to the system. As this was after 5 pm, I was told the contract would only be approved the next day. I went back the next day after receiving the approval SMS and asked for the Huawei P9 handset (after we originally chose the Q60), still thinking it was 64GB as I was told the previous day. Only when I got home and switched on the device did we see it was, in fact, 32GB and not 64MB. I went back to the store to return the handset and terminate the contract, as I would not have chosen the handset if I knew it was 32GB. The salesperson acknowledged the system showed the device as 64GB, but referred me to the store manager, Shireen Palm, who said I must log a case with Retention Department. No feedback for days, and only after I inquired was I told by the agent that the store must resolve the matter. I emailed the store manager and asked her to escalate this to her manager but have not heard from her since then. What was supposed to be my daughter's first new phone and positive experience has turned out to be very negative! I presume it is standard practice to provide the customer with incorrect information and then to refuse to remedy the situation. I will think twice before choosing MTN again for my next contract renewal.