I’ve just had my 7 year service +MOT at 58,000 miles. I bought years 6&7 in monthly instalments and I think the total cost was £700 so I had nothing to pay this time. It did not include plug changes. I’m not buying any more in advance as I think I may change the car this autumn, although there’s nothing wrong with it. If I keep it, no doubt I will need to change the plugs and the front discs and pads at some point, which will be costly. On the other hand, if I change it I will lose the £30 pa road tax benefit. Decisions, decisions!