Upgrade issue and package rate

Last year November I was due for an upgrade. We went into the office at Canal walk and they did the neccessary documentation. After sitting for about an hour and choosing the package we wanted and the new cellphone ; we were told but the guy that we were on the ' old system ' and Mtn has a 'new system ' for that reason our upgrade could not take place. The guy advised he will send an email to mtn and ask to be transferred to the new system. The package and the monthly installment was R400. This was discussed with myself and the mtn employee. It was important for us to get data airtime wasn't important. He told us we can get 2g data and 50 minutes. We were happy with that and assumed when he said he will transfer us to there new system that package will.still be in place.Okay so.we left and he called us a few days later to say it's all been sorted and we can come and get the new cellphone. Not once did he mention it's not the same package; not once did he say you will get less data. That was never discussed. We only realized this when we got our new airtime and data the next month. We paying now R400 for 500mb data and 50 minutes. I mean who pays that amount for 500mb that will.last 1 day. That makes no sense. After this we contacted the guy and he said he will speak to management; nothing transpired . We called again and then was handed over by the supervisor. Few days went by and they said they cannot change the package as it was past the 7 days . How would we know if the data only comes through the next month. They have the worst customer service and was not willing to compromise or assist a long standing customer. There service is pathetic and I.wpuldnt recommending them to anyone. We asked 3 weeks ago for cancellation for the account; they still haven't come back to us