Vodacom App not safe for the consumers

So I have 2 data routers. 1 is in Durban which my sister's daughter uses for online class and 1 which I use in JHB. In order for me to put data on these data Sims I have to put money on the Sims then they are linked to my vodacom app SD this is the only way you can buy to get the special prices. So R200 was put on the 1 data sim my sister called me to say can I please send her data via my app. I was busy with a class so when I finished around 5:30 I logged into my app only to discover that the data had been bought. When I called her she told me she had converted the cash to data off the vodacom site. That's impossible as that meant she had gotten access to my app on the site. So I called the call center which is a freaking nightmare. After telling the tobi to f... off it finally around me to speak to a consultant by the name of Connie Maoba she tried everything to help me and eventually went to her supervisor Sebolo who was not interested in finding out how someone else was able to access my accounts. This is an infringement on their agreement with me. I want answers and they won't give it to me. NO client is safe using the vodacom app as anyone can use your details.