bridge of contract

I recently got a loan and a credit card from Woolworths, both these were processed on the same day, my problem here is the fact that woolworths had been debiting my account for the loan and has been notifying me of anything partaking this account, recently I got a letter telling me I have been handed over for not paying my credit card. what I don't understand is why I was not notified of over due payment and most importantly why did woolworths not debit my account for this as per the agreement on the contract, I did not bridge the contract as sufficient funds were available on this account on the 27 of every month so why they debited payment for 1 account and not the other is beyond me, I went into store to resolve this and I was told my bank cancelled the debit I contacted my bank and I was told because this was not a stop order but an arrangement I made with woolworths there is no way they can cancel but only reverse a debit. I need to know why they are tarnishing my credit scores when the fault is an admin error on their side and finally I need to know whats woolworths is gonna do about this