Guessing the numbers they deal in, I guess it's not unexpected that some go astray. I do note a small 'insurance' charge is levied,
perhaps you could test this out @Davey44 ?
I find that delays are semi frequent but the vast majority of the items that go astray do turn up eventually. On the couple that I have had I have flagged with the sender and they have asked me to wait a while. After that they have replaced them without question, and in a least one of those occasions it eventually turned up after another month.
I am only a private individual who sends/receives an average amount of stuff. In my experience (limited as it is) and in my belief (backed with no evidence) very little is truly lost in the post if properly packaged. A few bits get separated from packaging, but much of what is claimed to be lost is either never sent or is received and claimed as not.