(a) Entire agreement.–Except as provided in section 6329(c) (relating to add-on sales), a closed-end credit agreement shall contain the entire agreement of the parties regarding the costs and terms of payment for the goods and services, including a promissory note or other evidence of indebtedness between the parties relating to the transaction.
(b) Signature.–A seller may not obtain the signature of the buyer on the agreement if the agreement contains blank spaces to be filled in after it has been signed.
(c) Installments.–A closed-end credit agreement may provide for unequal or irregular installments.
(d) Incorporation by reference.–A holder may, in a buyer’s subsequent closed-end credit agreement, incorporate by reference the buyer’s previous closed-end credit agreement and a description of the collateral for the items purchased under the previous agreement.