Double billing and no answers!

I have 2 contract phones with MTN, both on the same bill.<br> <br> On the 1st of February, I upgraded the one to a cheaper package (from R259 to R179 p/m), while keeping the other handset. At first their system was offline and they could not process the upgrade. I went back the next day and after them being on the line with their support side I was told I could take the phone and again return the next day to sign the paperwork, which I did and I assumed all was well. <br> <br> Come billing time end of March I was charged a double upgrade fee (R105) and still the origional price for the upgraded phone. They credited my account with one upgrade fee and promised that the new price of the phone will reflect e/o April. I upgraded my second line as well, the new package R330 p/m.<br> <br> Got my bill today - a rediculous R691! How is that even possible? I paid my upgrade fee in advance and am still being chagred for the old handset price on my Feb upgrade.<br> <br> I did not even receive a detailed bill, only an SMS to say what my dues are. If I refuse to pay them, they simply cut off the line. Time to name and shame, I have had it with the promises and promises of call backs that never happen. Sort this out!