Unathorised Debit Orders

Good day

I trust you are well. I have an issue with a debit order for the past 3 months by Gravitylei. I do not know who this company is and who has given them authority to debit my account. I have contacted Absa to cancel and reverse this transaction and every month they say I should call the company and they give me a number. The number has changed every month. I have received a contact number for Gauteng and Durban and no one ever picks up the phone. I really want these transactions reversed and get my money back and the debit orders to stop going through my account as I have not authorised them