Can a bank legally discharge its duty to assist customers in financial hardship by selling their debts to a third party?What if that third party is a debt collection agency notorious for its refusal to negotiate repayment plans and for its "unscrupulous tactics"? Is the bank in any way liable for those actions?National Australia Bank may well find out the answer to these questions as Victoria's Consumer Action Law Centre has recently complained to ASIC about half a dozen cases involving Accounts Control Management Services.The consumer lobby is also ramping up a media campaign targeting NAB and ACMS for bad behaviour towards customers in financial difficulty.ACMS buys bad debt off NAB and Telstra. Debt agreement administrators, financial counsellors and consumer groups all seem to agree that ACMS is by far the most aggressive of the major debt collection firms.In the past week The Sheet has spoken to three former NAB customers who have had their credit card debts sold to ACMS. All three have apparently been told by ACMS that repayment plans are not acceptable and that the collection agency will accept only repayment of the entire debt, plus apparently exorbitant ACMS fees and charges, immediately.All three debtors describe threatening telephone calls, often multiple calls per day.One debtor, Karen Madden, a sales rep from Mont Morency in Melbourne's east, said she had made more than $2000 worth of repayments to ACMS on a credit card debt that started out at $4000 when it was still with NAB. However, when she went to court last week to defend herself against enforced bankruptcy, ACMS denied that any repayments had been received."When they found out I had a home and was paying it off, they immediately demanded repayment of the entire debt, which they said was now $6000," Madden said.Consumer Action highlights a case where they say they caught ACMS out by recording phone calls made by a debtor offering to participate in a repayment plan. ACMS later claimed in the Victorian Consumer Affairs Tribunal that the debtor had not responded to more than 20 letters and phone calls."Yes, NAB have a responsibility and when we spoke to them about ACMS they just shrugged their shoulders and smiled," said Gerard Brody, deputy director, policy and campaigns at Consumer Action Law Centre."The bank has a legal obligation under the Code of Banking Practice to assist customers in financial difficulties. It should not be able to duck this obligation by selling off debt and failing to take responsibility for the conduct of the debt collector."Just because ACMS is a licensed credit provider doesn't diminish the fact that the original debt was with NAB and their obligations continue."We also want ASIC to start to enforce the guidelines for debt collection a bit more vigorously."