Telkom refuses to give me a paid up letter and my deposit paid after termination

Telkom blacklisted me after I terminated my landline and internet service after numerous problems. They hold a R700 deposit and refused to set the deposit off against the final amount due. I have paid them now the amount t that they requested, and am unable to get a paid-up letter out of them to remove the listing form ITC. I intend to sue the CEO in the Small claims court for my deposit, and they conveniently forgot that they are holding on to my R700