Contract upgraded without my knowledge

i was going through my vodacom app. only to find one of my contract *** has contract expiry date of 2017,this data line was now on a month to month contract. I phoned vodacom customer care only to find the line was upgraded on the 9th January without my knowledge. i was given this number by the agent: *** saying they are the oneswho upgraded the line. i did not call. i would like vodacom to attend to this matter urgently as a loyal customer and as my service provider.