Thanks for that, I've the erWin documentation pack for my 2011 S4 and my wife's 2015 VW Polo 1.2TSI, and grabbed a copy of the Leon one in this site's
resources area, unfortunately, my PHD daughter and her PHD husband don't have any need/use for that info pack for their Arona - but as a father, I'm trying to protect them from not looking after their first car or getting fleeced by garages.
They are extremely low annual mileage car users either working from home or using public transport to get into their offices in Central London, so the air filter nor the spark plug changes will be very critical, that Arona has "Iridium" spark plugs and from my past experiences, while "normal" spark plugs are recommended to have a 4 year or 60K mile service life, iridium ones cost more and are normally given a 6 years or ??K miles service period. At the end of the day, while I am willing to source the air filter and plugs and have them pay for them, I'd be fitting these parts FOC - so I'm stuck with not wanting to request that they cough up cash for parts that are not "now" due for replacement as far as SEAT's recommendation quote. Younger people, I find, tend to be minimalist when it comes to spending time and money on anything that does not absolutely have to be done, even when using the car's manufacturer's recommendations.
Haldex fluid changes, yes, I still have that job to carry out on my older daughter's Leon Cupra's front differential, I've bought the fluid and new drain/fill plugs and everything else needed to remove the pump and clean it - and now the warmer weather has arrived, so that job should get done soon!