(6) Where the Comptroller pays an amount to a person or applies it against an outstanding liability of the person, as a refund or other payment under this section or section 13 or 15 or as interest thereon and that amount was not payable to the person, or exceeded the amount that was payable to the person, the person shall repay the amount or excess, as the case requires to the Comptroller immediately after receiving it, together with interest thereon at the prescribed rate for each month or part of a month from the date on which the Comptroller so paid or applied the amount and the day on which the person repays the amount or excess, as the case may be, to the Comptroller.