<human>: About two weeks ago I sent a letter via "airsure" royal mail to go from the UK to Canada.  It was supposed to get there in 4-7 business days but it has not arrived.  The airsure service is supposed to be their more secure option that is "traceable" the whole way.  I sent about $2000 in checks that cannot be reissued - which in hindsight have used courier.  The only thing that royal mail can tell me is that according to the tracking it has not left the post office it was sent at.  I have been to the post office and they said that all letters have to be accounted for so that they are not missed when they leave the post office and therefore they believe it must have left.  I am fairly certain i know what happened.  The employee that served me put the letter to go out with the general 1st class mail and therefore it has got mixed in.  Apparently the post office manager said that they are supposed to place the letters in a box under the table, however, i observed the letter being put in a bag in the back. There is a return address on the letter.  I would do almost anything to get this letter back even offer a reward.  To make this sting a bit more these are bursary checks for university!

Anyways here are my questions
-  What would happen to a letter if the above happened?
-  How hard will they actually look for it if I do go ahead and make a claim?
-  Is there anything else I can do?

Summarize the given text in a few sentences.
<bot>: Sent a letter with $2000 of non-reissue-able checks via the traceable Royal mail airesure service only for it to be lost.