Held hostage by Telkom ISP

I am on a month to month internet data package with Telkom which I am trying to cancel with no success. I called customer service, they say to cancel online which it’s not allowing me to do. I called customer care again, they asked me to fill out a cancellation form which I did and emailed to them twice with no responses. I can’t get a new ISP until Telkom releases my line. I am held hostage by Telkom as they not cancelling my package.