The following clauses in their T's & C's probably apply.
8.2 Wherever possible, previously used or owned goods ("Used Goods") will be highlighted as being so used on the Supplier´s website at the time you place your order. All Used Goods supplied by the Supplier are warranted free from defects for 90 days from the date of supply (unless otherwise stated). This warranty does not affect your statutory rights as a consumer. If Used Goods develop a defect during the 90 day warranty period, you should follow the Supplier's Returns procedure (see condition 12 below). In the event of a valid claim for a defect in the Used Goods, the Supplier will (at its option) either:
8.2.1 replace those Used Good(s), if the Supplier has available the same Used Goods(s) at the same price;
8.2.2 repair the Used Good(s); or
8.2.3 refund or re-credit you the sum you have paid for the relevant Used Good(s) within 30 days of the date that the relevant Used Good(s) are returned in accordance with the Supplier´s Returns procedure (see condition 12 below).