Miss

I had a bad service at MTN online the lady called me to offer me a better data on the same amount am pay, I asked her if the won't be extra costs since I know that I must pay the pro rater, she said know, comes monthend the amount is not what we're agreed about, I call MTN no help went to the store no help they are telling me to resolve it online yet the know I can't get hold of them, I send emails no answer, am worried cause it's my name that is being gambled with MTN keeps on sending me Sms that I must pay them, how do you pay something that you ddnt agree with.. Bad customer service by MTN I have being there clients for 18 years now