MTN are *****ing peoples money

On the 3 of January I upgraded to a MADE FOR ME M contract with a Samsung Note 8 Headset. The total amoumt for this contract was 799 a month. I am now being billed for 1300 a month for this contract. To start of with I had to wait 5 days just to do the upgrade. When i phoned 808 they told me i must phone the store where I did the upgrade to assist me. When I phoned the store the lady there told me I had to phone 808 to get this sorted out. My billing for the past 3 months have been incorrect. And NOBODY from MTN can sort it out. Today I phoned their Head Office. I tried 27 times( have screen shots of my call log) they only let the phone ring or they pick up the call en then drop it immediately. The lady at the store where i updlgraded told me to go to the store with my contract so that she can help me to phone 808 but the person who did my upgrade never gave me a copy of the contract.