MTN South Africa empty promises ( false advertising)

This is the second review I am writing about MTN since I took up my contract at the Sandton City Shop on my 1 December 2018. On take I was supposed to get Free Pass data of 20GB as advertised on tv and eve where else. I have been to the shop 4 times all for different complaints. Last time I went there was Saturday 8 December 2018 where I spoke with Sheppard the guy who assisted with contract take up. He assured me everything will be sorted by close of business 10 December 2018 and that was not the case. I made follow directly with him and response I got is I am not the only client MTN has so I must. I must say the contract is barely a month old and I want to cancel already as I am very frustrated with their service. Anyone please assist even if it’s advise on how I can cancel this contract.