12. An employment business shall not, in respect of a work-seeker whom it supplies to a hirer, withhold or threaten to withhold from the work-seeker (whether by means of the inclusion of a term in a contract with the work-seeker or otherwise) the whole or any part of any payment in respect of any work done by the work-seeker on any of the following grounds—
(a)non-receipt of payment from the hirer in respect of the supply of any service provided by the employment business to the hirer;
(b)the work-seeker’s failure to produce documentary evidence authenticated by the hirer of the fact that the work-seeker has worked during a particular period of time, provided that this provision shall not prevent the employment business from satisfying itself by other means that the work-seeker worked for the particular period in question;
(c)the work-seeker not having worked during any period other than that to which the payment relates; or
(d)any matter within the control of the employment business.