MTN AND MY DISSAPEARING DATA

I have a contract with MTN for a data sim card for my laptop. For the last five months I have been visiting the Somerset Mall store complaining that I loose all my data within a few days of my monthly allocation and having to buy more which also dissapears. All they can tell me is that it has been used, that is something I already know and why I am in the store to complain. last week after loosing 1.5 gigs overnight when both my laptop and internet connection was switched off I went into the Waterstone branch where they were very helpful. logged another problem ticket and advised me that I had to go back to Somerset Mall and speak to either Alison the manager or, the data specialist. Every time I visited Alison was "on lunch" and when I asked when she would be back the reply was "don't know". I asked if I could make an appointment to see her and was told no. So, I had to deal with the "data expert". A more unhelpful person I have never met, he sat pecking at the keyboard without speaking to me and after about 20 minutes told me I lost my data overnight on the 20th December. This was what I already knew and told him it was impossible since the laptop was off and the connection was not attached (a story I have been repeating ad nausea for five months) and what was the solution? He just looked at me and said "its been used". At this point my husband told me I was, once again, wasting my time and getting upset without anyone doing anything and we left. As we left the so called "data expert" turned to his colleague and started laughing at us (my husband had turned around and saw them do it. I have never been so furious or treated so badly in my life. I will never go near MTN for anything ever again, they do not deserve to have my business and do not care for their customers, in fact, treated me with contempt.