VODACOM- DATA THEFT AND DIGUSTING CUSTOMER SERVICE

I opened up a contract with them I think it was either March or April of 2020, purely for an IPHONE for my daughter, I kept the sim card in my phone. There was a 60 min call per month limit to this contact, no data deals. I was then retrenched in May of 2020, but continued to pay the monthly fee of approximately R560, cant remember exactly. On the 1st of Feb 2021 I found temporary employment, In March 2021, my phone was ****** out of my handbag, with the Vodacom sim card in it. I completely forgot about the sim card as the company I was working for provided me with a company phone, and I continued to pay the Vodacom the monthly contract fee. In April of 2020 I received my account statement with an amount of R10 000??, when I called to query this I found out that the person who had my ****** phone had used up data to the value of R10 000 in less than a week?? I still could not remember at that stage what had even happened to the sim card I just completely forgot, I started receiving endless calls from VODACOM, I had to explain my story to about over 10 different people every time that they called me, I used to receive at least 5 calls a day from 5 different people,I told every single person that ***** was committed on my contract, can you imagine explaining the story every day to so many people, and no one would make notes so I had to repeat myself all the time, eventually I stopped answering calls. I even emailed VODACOM an affidavit as per their request to justify my story, I sent an email informing them that there was ***** committed on my account. Even after I submitted everything they requested via email, I was receiving numerous calls from them again every day!! My question is, data availability was not even part of the contract and even if there was, none was used, I asked them to go back at the history and see that no data was used and how is it possible for someone to use up R10k of date in a week?, I never needed data, I had WIFI at work and home. Subsequently my employment contract ended at the end of Sep 2021 and I told a few of the VODACOM representatives that called me about that, they said that I need to pay at least 10% for the outstanding amount, I told them not until the ***** dispute has been resolved. Now they have handed me over to a collection company, but still no investigation has been done on how it was possible that my ****** phone with the sim card ran up a data bill of R10K??