You can't do anything about this in person. Your adviser has sent it, so it's up to HIM to follow up with whatever means he used - courier company, the mail company - and to push INZ to find it if it is proved it was delivered. Although the document is ABOUT you, it is not directly your business, so the courier company etc. won't accept instructions from you, and you've also told INZ to deal with the adviser on your behalf. You need to let your adviser act FOR you.
In your place, I would be asking the adviser these questions. Another thing you could ask the adviser is if he thinks it would be a good idea to be getting another issue of whatever the document is, in case it doesn't turn up. (If the adviser is making a fuss with INZ about their not finding the thing, I doubt that they would prematurely decide your case for lack of it.)