If all they will do is the same as what would be done in the UK then why send them back?
If they are replacing with new wheels with the correct fitting then fair enough.
Just in case, maybe mark one or two of them. Just something small to make sure they don't just re-drill and return.
To be honest if what I get back looks fine I will be happy, I am confident and trusting enough that a manufacturer that prides themselves in quality and service will do the right thing.
If they look wrong or botched I will kick up a fuss, but they are the expert and they have all the machinery to do it properly.
It is actually probably more hassle thinking about it for me to sort in the UK, as first I need to find somewhere, then when I do, can I trust them, then I need to get them there, get them back, get the invoice cover. It is just easier to let UPS collect them and drop them back off in a couple of weeks time when they are either replaced or re-manufactured.
I am fine either way, as long as it looks spot on and is safe and on the safe aspect I would fully trust the manufacturer to do the right thing, one would not expect them to chance their reputation especially on a set of wheels that are for sponsorship purposes.
It seems a bit strange that they seemed happy to advise you to just take them and get them redrilled locally when the general reaction in here has been

WTF.
To them it is their living, something they can do with ease and have all the correct machinery. The guy mentioned they put them in the machine, code in a few settings and 20 minutes later all done.
When I explained that here in the UK I know of no one, he quickly suggested to get them back to them as what is a simple job for them might not be possible for others or may not be done correctly. Shall see what comes back, end of the day if I am unhappy I just do a claim via payment processor which was paypal, but I did explain to them this car gets raced on the race track so if any strength to the wheel is lost it would be a major issue, the response was no integrity is lost. It is there wheel, they make them from ground up and know what is and what is not possible, if I was a manufacturer of wheels I would question it, but I am not and as such I trust the manufacturer to do the job right. They made a simple mistake, now they can put it right and hopefully correctly.
