Charged for ADSL that we don't use

Been trying since November 2017 to cancel our ADSL line, which hasn't been in use, yet we are being charged for it. My dad is the account holder and he's been into a Telkom store to cancel. They've told him that they can't cancel in-store and he needs to do it online. Haven't been able to create a profile online, as the setup process doesn't go past the 'Next' button.