I think it's about every 6 months they offer discounts.
The good news is that SEAT have recently announced 20% off service plans, including the All-in plan:
SEAT Servicing - Service Plans Online. Spread the cost with SEAT's aftercare servicing for older cars. With our expertise you really can go all-in. Find out more.
www.seat.co.uk
@Syphon - you may wish to promote more widely?