No resolution from Vodacom despite repeated requests.

In the last month, I have contacted Vodacom five times already for assistance with resolving call issues with my phone. My clients try call me but they are unable to get through to me or even leave a voice message. On their side, the call usually cuts after three or so rings and on some occasions, rings longer and then cuts abruptly as if the call has been deliberately cut, which is not the case. On my side however, I receive no notification of the attempted calls and my phone does not ring at all or give a record of unanswered calls. I have contacted Vodacom call centre numerous times to resolve this issue but to no avail. It was suggested that my phone could be the problem, and I swapped phones, but still have the same issue. The latest development is that callers try call me and it rings from their side continuously without taking them to voicemail but on my side, the phone does not ring and there is no record of any calls made. I am at my wits end as important clients and my family struggle to get hold of me. Please can a knowledgeable contact in Vodacom assist me in resolving this issue. Thanks