MTN Contract ***

I have been using MTN for so many years now and I never experienced any difficulties, but after my latest updates I have been receiving bad experience,

I have signed a contract of R299 and I have been paying it honestly every month, but every month they suspend my phone saying that I have an upstanding account which I don't know of

I have been calling them and they always promise to fix it for me they tald me to send email the copy off my contact repeatedly but no response from the email as they promised.

Every month I have to call them so that they open my phone but this month until today my phone is still offline and I don't owe anything since I have paid already but thy didn't open they say I must send proof of payment which I did but still no response yet phone is offline