Thanks for your replies.

The SSL issue was just a temporary problem when I first attempted to make the booking.

All the names on the paperwork seem to be in the right order. Everything looks OK. I tried looking up my reservation using my first name rather than my surname but that did not make any difference.

One other slightly odd thing. When I first contacted United by email it was forwarded to the MilesPlus team. Which is odd because I hadn't joined Miles Plus. I got a reply saying the booking had been added to my account. But it did not address the confirmation number issue. I have now joined MilesPlus in the hope I will get a better response.

I'm starting to get a sinking feeling over this!

Grateful for any further advice.