NEW contract

I took a new contract out in may, I was given a new number with the phone only to realise each day that I received some other persons old number. I get wrong number phone calls at 2:00am and 3:00AM in the morning all looking for the same person. I also get unpaid account messages for this same person. I have phoned Vodacom regarding this and all they say is, there is nothing they can do about it!!! If I want a another number I need to pay for it???? I took a NEW contract out!!!!!