Stop unauthorised debit order

I received a text from Capitec this morning the 24th November stating that there is a mandate on my account regarding a debit order that will go off on the 27. I didn’t sign for such. I called Capitec immediately and the lady that I spoke to told me I’ll have to go the beach told her am not around so how then do I go the branch. She had no solution. Spoke to Kamvalihle on WhatsApp he gave me the contact details of the the company who supposedly debuting my account number doesn’t exist. All I want is to stop the debit order with immediate effect and for future but they have failed to do so.