Vodacom Spam Calling and Hanging Up

I keep getting calls from Vodacom on a daily basis and when I answer there is dead silence and it disconnects and it is a huge annoyance.

I am not due for an upgrade, and my account is up to date so why are you spamming and harassing me constantly by phoning and hanging up.

I would like to block these numbers but what if there is a valid problem in future and I don't receive the legitimate calls because I blocked these annoying spam calls - You are a legitimate business so why is it needed to play these childish games with people that dont have time for this **** on a daily basis.

The following numbers amongst others are the worst: ***, ***, ***, ***.

These are all flagged as legitimate numbers by Tru Caller.

Could you please put a stop to this immediatley