debit my account with 7556 and then because it is there mistake

Alll i want is a letter from them stating that the amount deducted was not authosised which they dont want to give me its now almost 10 days to get this letter .i mean how do i give permission to deduct 7556 from my account . All i need is a letter to show to my bank that this was an error .2 days later i paid my account as per settelment letter please send someone to collect this dstv from my house i m sick and tired of multichoice no customer services .spoke and mailed +/-15 agents even visited walkin centre still no positive letter from multichoice same story they will escalate and come back still waiting