This seems to be a glitch on Argos website.
They currently have the following offer if you purchase selected PS3 games:
Save 1/2 on either PS3 Controller Dual Charging Station (566/8980) or PS3 Compatible Wireless Controller (568/0542) when you buy this game. To receive this offer add both items to your trolley. Offer ends 23rd July 2010.
But when I added the PS3 Blu-ray Remote Control (item number 568/3790) and the PS3 Controller Dual Charging Station (566/8980) both in the basket this is what came up:
PS3 Controller Dual Charging Station. 566/8980 1 £0.00
HP Photosmart Premium. 670/4623 1 £99.99
PS3 Blu-ray Remote Control. 568/3790 1 £16.00
Includes special offer saving (if you buy all items together at one store): £9.99
Hope this helps someone