You're not really supposed to have a locked bag going to LHR. TSA-certified locks are fine if the TSA guys have nothing to do and can run around fiddling with keys in locks, but they are allowed to cut through the nonsense when they're in a hurry and have a lot of bags. As far as I know, you are not entitled to compensation. In future, if money is a concern, use ziplock ties. They're pennies each so it is not an annoyance when an officer cuts the tie. You will have plenty more packed away so you can again "lock" your bag against petty pilfering on the tube or what have you...but if you're traveling by commercial air, the first rule is that you have already agreed to a search and the second rule is don't be a nuisance. A lock, even a TSA approved one, certainly violates the second rule in the eyes of many officers because it wastes time. So they cut it.

I feel like the sellers of these TSA approved locks are scammers and know they are, and I wish the whole enterprise of selling these locks would be shut down, but travelers are viewed as acceptable marks for these small rip-offs, and too frequently it is allowed to sell us useless junk. Let the buyer beware!!!