What happens when police lose stolen property?

We were burgled a couple of years back. We gave statements which detailed the stuff that had been taken, mainly jewellery. Some stolen property was retrieved via a pawn broker, we weren't told exactly what, and how much . We were told by the sergeant dealing with the case that it would be used as evidence in court. The burglar was prosecuted and served time, and the the investigation seems to have concluded. We have made a number of enquires as to when we would get our stuff back and originally told that it would be retained in case of any appeal etc. I have made recent enquiries since then; however, now we have been told that there is no trace. It seems they have no record of what evidence they held and it may have been lost in the system. I am considering some kind of complaint, but what happens in a scenario such as this, is there any kind of compensation for this? I was please the police nailed him, but It seems a bit wrong when the lad who done it is now walking round town still on drugs and will likely commit a similar crime again to feed his habit. Alot of the jewellery had sentimental value more than anything.