From a site moderator:
Posts from new members asking for comments about a particular service provider have a strange habit of being followed by posts from other new members saying how wonderful that service provider is. (i.e. it's 2-part spam). They occur almost daily here, which is why Baldric thought you might be a spammer.
However the posts are usually written in 'Asian English' and refer to services in, say, Bangalore(although they also seem to refer to Australian, Canadian and American companies). Your post, referring to a UK Groupon offer (I assume) seems genuine enough to me.
I'd be a little concerned about only a 2.5 out of 5 rating on Groupon itself:
https://www.groupon.co.uk/deals/bos-vip-ticketing-1#tips
and also by the rather strange reviews of one particular garage operated by them:
https://www.groupon.co.uk/biz/greenford/bos-vip-ticketing
You need to remember that many garages are only too keen to give free (or highly discounted) inspections of your car because they can then find lots of jobs which 'need doing' and which they can then charge you lots of money for.
I'll be sticking with my trusted local garage, I think!