The limits of how far chargeback rules can be extended are to be tested in a complaint lodged with the Financial Ombudsman Service over a disputed student loan.The Consumer Action Law Centre is acting for a borrower, Shannon Squires, who enrolled in an IT college and was referred by the college to National Australia Bank for a A$20,000 student loan.The operator of the college, Excom, went into administration last August, and Squires was unable to complete his course.NAB continued to demand repayments. CALC's claim is that when NAB approved the loan it established a "tied credit" contract.CALC is arguing that because Excom is unable to provide the service, the loan contract should be terminated - in much the same way that a consumer who does not receive goods paid for in advance can apply for a chargeback.An NAB representative said it had provided loans to some Excom students but it does not consider them to be tied or linked credit."Students took out NAB personal loans to cover their study costs, including course fees, personal computers, text books and vehicles," the representative said."While NAB has never had a contractual or financial relationship with Excom, it will work with the Financial Ombudsman Service and the Consumer Action Law Centre to investigate these claims and ensure a fair outcome for its customers."