It depends what there is to sort out. Without the council's explicit support, the chairman did not attend the meeting as a council representative and did not have the power to make any decision or commitment on behalf of the council. Any claim to have done so is invalid.
Any decisions made by the outside body whose meeting it was are valid but in relation to the council, nothing has changed. If there is a problem with arrears, then in the absence of payment, the problem still exists and the payment is still owed.