***** on my account

Hi, i just received my vodacom bill and there was a big data amount on it for one of my numbers i dont even used, vodacom just lifts their arms but i refuse to pay that, I only use 2 of all my numbers, *** and *** so there must be ***** on this number *** please investigate as i wont pay this, i am already in financial crisis already as youl see on my account and if this gets billed to me I might as well just close all my accounts and freeze them I dont have they money to pay 8000 and there is no way i will be able to manage that amount. Also long ago i put a block for R50 on that number just for in case something like this happens