Endless trouble after Vodacom VOIP phone was hacked

Vodacom installed my new fibre optic connection and VOIP phone during November 2017. The system was activated on 27 November 2018. At about 02:00 in the night on 28 November 2017 my phone was hacked and international calls made to the value of approximately R 5 000. This was reported and a reference number was provided. The costs of the hacked calls was billed against my first account. I have been in contact with Vodacom to inform them that I am going to revers the debit order payment on my account. My service was then blocked. I have spend many hours on the phone with Vodacom consultants - all in vain. My service was temporally be re-connected but the problem has not been resolved as yet - approximately three months later. I have made calculations and paid the amount that I believe I am responsible for. On 1 March 2017 I received notice from the Vodacom Collections Manager to inform me that if I do not pay my account within 7 days my service will be blocked. I have contacted their collection department and they indicated that they can not solve the problem as it is the responsibility of another department.