If the Project Manager fails to issue an Interim Payment Certificate in accordance with Clause 16 (v) or the Employer fails to make payment in accordance with Clause 16 (vi) the Contractor may, after giving not less than 21 days’ notice to the Employer, suspend work (or reduce the rate of work) unless and until the Contractor has received the Interim Payment Certificate or Payment, as the case may be and as described in the notice.