Unauthorised debits with no answers!

My mum (a pensioner) took up the annual subscription offer on her DStv package in April this year however Multichoice has been debiting her the annual premium amount every month since. I queried this months ago and was escalated to a manager in the call centre who promised to address it and provide feedback yet nothing has been done to date. I called in yesterday again and was advised a supervisor would call me within an hour and nobody has contacted me yet. I've also e-mailed Multichoice and received acknowledgement that a response would be provided in 24 hours but once again nothing. It appears the annual premium offer is either higher grade math for those at DStv or a scheme to intentionally de***** customers, including senior citizens.