Where -
(a) a hirer is entitled under section 10 of the Principal Act to appropriate a payment made after the commencement of this Act, and
(b) the hirer fails to make an appropriation under that section, and
(c) one-third of the hire-purchase price has been paid under each of the hire-purchase agreements in respect of which are due sums in or towards the satisfaction of which the entitlement exists,
the owner may, notwithstanding the provisions of the said section 10, appropriate the payment in or towards the satisfaction of the sum due under any one of the agreements or in or towards the satisfaction of the sums due under any two or more of the agreements in such proportions as he thinks fit and, if he fails to make any such appropriation as aforesaid, the payment shall, by virtue of that section, be appropriated towards the satisfaction of the sums due under the respective hire-purchase agreements in the proportions which those sums bear to one another.