MTN lack of service delivery

On the 13th of May 2018 I went to the MTN shop in Three Rivers to upgrade my contract. The lady at the counter helped us with our decision- the package included 2 Huawei Smart phones: the package was Standard with Top up, 24 month MTN MyChoice flexi 55. It was explained to us that the principal phone was on contract for R471. 00 and the second phone on top up with a monthly prepaid airtime given by MTN of R55.00. Contracts were signed and cell phone number ********** was allocated to the second phone. We recently noticed that the number ********** is suddenly not working and we don't receive the promised R55.00 airtime. I phoned the number and a very annoyed gentleman answered and said the number was allocated by MTN to him. On the 1st of September 2018, I phoned MTN's call centre and the consultant did not know what was going on and referred us back to the Three Rivers shop. We had to wait a very long time as there is only two sales ladies working in the shop. When it eventually was our turn, we explained our problem. She went into the system and after a very long time set up a new contract- because she "can see what happened and do not know what to do". Apparently Head Office cancelled the number and allocated the number that was given to our second phone to someone else? She promised to phone us back at the latest 2nd of September 2018 with the decision of Head Office because she had to log a query. No 1: why did she not phone Head Office while we were in the shop? No 2: How can MTN just cancel a number without notifying the client? No 3: How is it possible to cancel the number if one of my family member's is still using it for Whatsapp? No 4: The sales lady did not phone back and if she eventually phones back- will I be liable for a contract fee per month? What about all those R55.00's that I lost due to someone's incompetence? Why must I then return to the shop to get a new sim card with a new number? I just want to express my utter displeasure with MTN and the sales team of the shop in Three Rivers- I would like this matter to be sorted out and get a satisfactory explanation what happened- not a lame excuse "of I do not know"! MTN is a big company with a huge client base- how is it possible that a mistake like this happen and none of their employees can help me directly?