bad credit due to incorrect debit orders from voda

in December 2015 Vodacom deducted a debit order twice from my bank account. when I phoned the bank they said they cannot reverse it and that a lot of people has been affected by this. when I phoned Vodacom they said that it was an error on the bank side and that I need to reverse the one amount myself in the bank, which I did do in the bank. there was no payments in arrears at all and I had a clean record at Vodacom for years now. after trying to get a tablet on contract last month they denied me due to my payment history on December. why should I be penalised because of an error on Vodacom side done in December? I did ask Vodacom in Mayville to query this as it was their mistake and not mine nor the bank's mistake. in short I decided not to take the tablet on contract anymore as I will try with MTN or Cell C as I had for years a good name with Vodacom and my payments always reflected paid on time and not missing a payment. they made a mistake December and now I am showing as bad payment where in fact the one of the 2 payments was reversed and the other still was paid up