Vodacom did not cancel my contract

I had a data top up contract with vodacom. I've send them an email on 18 Feb to say that I would like to cancel the contract. I had to email them because I could not get through to their vodacom number for 2 days. I also went to the vodashop in CBD but they said I could only cancel via the vodacom number. I wanted to cancel my 5G MBB 24 M Top Up on ***. I got a reply from vodacom on the 20 th of FEB : Please note that cancellation has been loaded for 29/02/2016. (Reference number: EC-04Q2-2WOOOZ Cancellation of contract)<br> Then I mailed them again on the 22 th of Feb and asked for it to be cancelled immediately because I was scared that this would happen and I received the following mail from them on the 29 th of feb: Please note that cancellation has already been done. But now they've subtracted R389 from my account on 1st of March. This is a topup bundle contract so I pay upfront for the data - how can they subtract money from my account if it was cancelled?