My number was ported without my permission

I woke up yesterday with an inactive phone and I went to the Mall of the South vodacom shop. I was told that my phone number has been ported to another network. When I requested for more details as these was not authorized by me and I had no idea which network my number was ported to. I was told that vodacom have no trail of what took place as the porting happened outside their networks/ system. The consultant that assisted me instructed me to go to all the other networks and investigate which network my number was ported to. This was the worse experience as at the number in question is the number I use to access my on line banking. My biggest frustration was that vodacom could not own up and they distanced themselves from the whole incident and I did not understand how someone can port my number without vodacom being aware. The question is if people can port our numbers and by pass the process, this then mean that our information is not safe with vodacom.