Nothing contained in ss. 893.44 to 893.47 shall alter, take away or lessen the effect of a payment of any principal or interest made by any person, but no endorsement or memorandum of any such payment, written or made upon any promissory note, bill of exchange or other writing, by or on behalf of the party to whom the payment is made or purports to be made, is sufficient proof of the payment so as to take the case out of the operation of this chapter.