5An order may declare it to be unlawful, except to such extent and in such circumstances as may be provided by or under the order, to require, as a condition of the supplying of goods or services to any person,—
(a)the buying of any goods, or
(b)the making of any payment in respect of services other . than the goods or services supplied, or
(c)the doing of any other such matter as may be specified or described in the order.