SPEEDTWIN

I would charge them for the cost of changing the locks because you cant be sure who now has a copy and that is no fault of yours. I also always keep the barrels/locks i change and use them at a later date on another property but charge for new locks. I do it myselve so it is still a lot cheaper to the tenant than getting a locksmith tp do it. I get UPVC lock barrells from my local hardware store for about £10 and they are really easy to fit, just make sure you get the right lenght ones cos the doors are differance thicknesses (though you can make do if it is just a little bit shorter or longer just doesnt look good)