Treating Contract Customers like ****!!!!!

i am so disappointed with MTN, i had a contract which was handed over to Shapiro Shaik Attorneys for collections, i paid the R2000 which was outstanding, the Collection Company sent me a Statement showing my account is on ZERO Balance, when i sent that to MTN they advised i still owe them another R2300, which i refuse to pay, it was not discussed with me what the amount is for. my contract was R119 P/M how come now i owe them over R5000. treating us like TRASH, Giving us a Run Around from pillar to post. my number is ***. now I'm receiving calls from other Collections Companies. asking for the same amount that i have already paid. if this is how MTN Treat their Customers, Next I'm going to the Ombudsman , they can not mess my Credit Profile like this and get away with it.