(a) If authority to do so is contained in the contract or agreement, the holder of a retail installment contract or retail charge agreement may collect any delinquency, collection or dishonored check charges, attorney fees, court costs, and disbursements. In this case, the charge must be reasonable, and no attorney fee may be recovered unless the contract is referred for collection to an attorney not a salaried employee of the holder.
(b) The contract may contain other provisions not inconsistent with the purposes of this chapter.