Bad services

I took a contract with Vodacom and my contract number is ***,every month and convert my airtime into data,In January 2020 i dial *111# and choose option 2.to convert my airtime into data, Vodacom instead billed me for two months and the bill amount to R1000.00 and i couldn't understand that because there is no way an extended contract can be taken via an SMS, withouth signing any formal contract, if i want to add something to the contract which is not part of the initial contract the option should deny me that access,like any other options which are not valid for a contract,i felt like am been ****** and misguided by Vodacom . There must block that options to contract users and enabled through a formal request. Vodacom must withdraw that R1000 billing into my statement