One star is too much for this organisation

I have been an MTN cell phone client for 16 years and data client for about 8 years. I am so frustrated with them that I am ready to cancel BOTH my contracts. On 15 May I did a telephonic upgrade (biggest mistake of my life). The consultant confirmed that I had been upgraded to the 30/30GB plan over 24 months at R399 per month. At 3pm that afternoon, I received an sms stating that “Your MTN application for an Upgrade has been approved and upgraded” This upgrade is still not reflecting on my MTN account. It shows that I am still on the 10GB plan. I have spoken to 3 different people at the call centre on 6 June ***) and no-one has been able to help me sort this out. I have received no response to the two emails that I sent in this regard Today - 26 June, I called in to cancel my contract, I was told that I have to pay penalties despite the fact that I have not received what it was agreed that I would get. MTN are probably the worst service organisation in the country. I'm done MTN.