Unknown contract

For over a year now we has have been unable to get any help with regards to a contract that was supposedly open under my mother's name without her knowledge. We have contacted Vodacom various time over the year to find clarity over when and where this contract was opened and they have given several different dates. My mother only had one contract that was on her name and that was the on a 072 number. We have no knowledge of a contract with an 083 number. Vodacom then handed the contract over to VVM attorney (a very rude company) and in August 2017 we sent VVM a police affidavit stating that she has knowledge of a 083 contract with Vodacom, VVM then did not provide any feedback with regard to the investigate they were suppose to do. And now 6 months later we are getting SMS's demanding payment for different amounts?! Is there someone that can please assist with this so that this issue can come to a conclusion.