Cancellation not effected 7 months

I signed a ONE YEAR contract with Telkom (ended Aug 2015) for Mailbox and internet services, as well as some business call bundle. When the year expired, we gave notice that we only need the phone line and the DSL line, and wished to cancel all other services rendered. We moved to another ISP and also move our website and mailboxes to them. HOEVER, it spite of repeated calls, letters, emails sent to the specific email address for cancellations - WE ARE STILL BEING BILLED for the services we are not longer using, and which we have cancelled. <br> <br> On what legal basis is Telkom refusing extending a contract and services beyond the one year term? On what legal basis is Telkom refusing to effect the cancellation, in spite of many, many calls and emails to that effect?