16.—(1) Where a person is required to pay a fee specified in these Regulations for an application, but fails to pay that fee, the Secretary of State may—
(a)reject the application as invalid; or
(b)request the person to pay the outstanding amount.
(2) Where paragraph (1)(b) applies—
(a)the person must pay the outstanding amount within 10 working days beginning with the day on which the request for payment was made;
(b)if the outstanding amount is not paid within the period mentioned in sub-paragraph (a), the Secretary of State must reject the application as invalid.
(3) The period of 10 working days referred to in paragraph (2)(a) begins—
(a)where the request for payment is made in writing, on the day that the request is sent;
(b)where the request is made by telephone or in person, on the day that the request is made.