I've been quoted £278 for changing the spark plugs by Audi,  following a service with them under a service plan, this is what the have recommended. This seems s lot if money to change 4 plugs, mileage is currently 55,000

I agree it's a lot. I'd recommend you get a quote from an independent garage 

Hello Martin,

It could be me, but I cannot see the economics stacking up when a 5 year old car gets serviced at a main dealer. 
As a matter of interest, how many services has the car had during that period? My guess is it’s just had its 3rd service, and as an aside it would surprise me that its air filter hasn’t been changed yet - but I could be wrong. 
Kind regards,

Gareth. 

Hi Martin,

I got a slightly lower price at £220 from an independent garage for the spark plugs.  And in the end i decided to do this myself (£50 for plugs and 1.5 hours of my time which i could have done it in 30 minutes TBH).  Which some say i am crazy to do whilst my car is still under warranty, but i'd like to think i'd take more care (I am a little OCD), and hey, it's been going fine for the last 2k miles.

Some not so great pictures if you wanted to do yourself.

I agree with Gareth, do you air filter as well.  You can do this for £10 for the filter and 30 minutes of your time.  Again, i've done this myself twice already.  Crazy that Audi recommend for me to change the air filter every 60k miles.

Thanks, Joe

I've been quoted £89 by a audi vw specialist which is more like it..probably cheaper plugs than audi, but you can by the premium plugs for about £60

Thanks Martin,

It could be me, but this does seem too cheap if the plugs cost £60. 
Not sure what you would term ‘cheap plugs’, but do you really want to have ‘cheap plugs’ fitted? 
Kind regards,

Gareth.