Vodacom taking money without authorization

I settled my Vodacom contact 8 months before the time and vodacom said i owed the R200 witch i paid at vodashop vaalmall the 28th of April 2016 and confirmation was send to vodacom but still on the 4th of May 2016 they deducted R200 from my.account without authorization.When i asked Vodacom call centre why she said i must go to my bank get a bankstatement and send it to them. I DID NOT CAUSE THIS **** VODACOM YOU DID SO FIX IT AND PAY ME MY MONEY