Who did he buy it from and when? If bought within 6 months from a dealer or trader, then the dealer or trader is liable. The details of the recall are:
28-9-2011: VOSA Confirmation of Injectors Recall. Thank you for notifying Vehicle & Operator Services Agency (VOSA) of the problems experienced with your vehicle. I can confirm the investigation into this fault is now complete.

Following detailed negotiations between VOSA and the vehicle manufacturer, VW-Audi Group (VAG) has agreed to replace all the injectors originally fitted to VAG group vehicles.

If any of the original injectors has already been replaced, VAG will reimburse customers who have paid for this work themselves even if thework was completed outside of their authorised network. If your vehilce is within the range of vehicles affected then all four injectors will be replaced free of charge.

To progress repairs and/or obtain a refund you should now contact the relevant VAG Customer Service Centre. If necessary, they will arrange to have your vehicle inspected at an authorised repairer free of charge. The contact telephone number you need to ring is 0800 08339140800 0833914 and ask to speak to Jenny Boyd or Stefan Elliott. VOSA will continue to work closely with the VW-Audi Group to ensure that this issue is concluded as swiftly as possible.