Cancellation of service

I wish to cancel my internet service but retain my landline. I sent the required docs (yes there are 3) to the designated email address on 7 July 2017. Service standard says 30 days but my Telkom router is still ticking away to itself as at 22 August!! I sent a follow-up mail today (twice) with read-receipt but it came back as UNDELIVERED due to full mailbox. There is no way that I am paying for the service for more than the 30 days since 7 July.