Both letters I had were sent to me and they included a sealed envelope to be given to the DMP, which contained the details of the additional medical tests required. You are notified to give the letter to the DMP who then is supposed to refer you for the relevant tests, etc. It's not clear if they notify the DMP separately, I suspect they do not as my DMP was otherwise unaware of the requests.
I hope that makes sense.
It sounds like they will need to reissue the letter. I think you should send a case-specific enquiry to London, marked as URGENT, telling them that you do not have the letter mentioned and you will need it to be resent. Presumably the deadline on that letter (if it's like mine) will be 90 days so in fact the deadline would be around today. I'm not sure what happens if the deadline is missed (I missed one of my deadlines but I managed to get the stuff to them before they kicked up any fuss about it).
Thanks for replying.....they said they will resend it...but it seems like we have lost out on three months
Fingers crossed you can get it sorted out!