Vodacom, out of bundle theft

So over the last 3 months I have been billed twice with out of bundle charges of up to R2000. Now I want to cancel my contract but Vodacom owes me money. I have visited a store in clear water mall and was told they can’t help me. I tried to cancel my debit order and was told they can’t help me. The call centre is useless and they file for investigation but I never get feedback. So who does one speak to in order to get reimbursed? Vodacom this has happened to several people in my close circle and these people have all since left your terrible service provider. Myself and all the people I am aware of were never out of bundle and yet you take from our accounts. This is ******** and theft. I am owed roughly R4000 and I would like to be reimbursed and I would like to leave Vodacom as a service provider however it is turning out to be an impossible task. DONT USE VODACOM AS A SERVICE PROVIDER UNLESS YOU WANT THEM CLEANING OUT YOUR BANK ACCOUNT.