Jump on the link somebody previously posted.
edit for link; Create - Missing invitations contact form (nhs.scot)
I completed it a few weeks ago and was told to wait for an envelope Just filled out again, had a text 5 mins later saying my appointment was in Moffat on the 19th June. Can't do that date so phoned the number on the SMS message, they answered within 5 minutes and I now have an appointment on Thursday morning at 9:36 in Dumfries.