********** activities

I keep receiving calls from Unknown Number, when I answer the caller hangs up. I am adamant this comes from Vodacom, as this happened several times when I was subscribed with Vodacom. Every time I get these strange call, some strange contract ends up in my name which I never requested! This happened 2 times when I was subscribed with Vodacom which led me to cancelling my contract with them for another Service provider. And now the strange calls are happening again, which I ignore