Spot lights- wiring HELP

Have got 4 spots on a light bar above the windscreen fitted by a local mechanic who I cant contact for two weeks. My problem is that the spots run on a stand alone on/off switch using two relay switches I can see under the bonnet ( I know bugger all about electrics!)..but when I switch the spots off, two of the four lights stay on.( they go off eventually but with varying delays up to 2 minutes after) I have changed the relays switches myself once already thinking they were the problem but a couple of weeks later the same thing happened.Are the Relays the problem ( do I need different types than the standard Halford ones) or is there something else I need to look at? Appreciate some quick response as I am taking the defender away this weekend...

Sounds like the relays are jamming, could be they are not rated high enough, and are "welding" themselves in the on position. The the relay out of the equation, join the spolight wires and disconnect them, do the light operate ok now? If so it IS the relay. Could you accidentaly have fitted a timed relay? One that remains on after loosing power for a while, although I doubt it since you say that the time changes.