Oil Cooler Leaking

I have a '98 freelander with a 2.0l L series engine. I've just been told by my garage that the oil cooler is leaking oil from where the thermostat housing is attached to it. The garage is bemused by this as the seal there is a water seal and should not be leaking oil. There is no oil in the coolant or vice versa, has anybody come across this before? I haven't let the garage carry out any repairs as they have quoted me around £600 to replace it. Does anybody know where I could get one at a reasonable price?

Be very careful sounds like the old squirty con job to me , a mate of mine took his motor to a garage to have new tires fitted, and after the fit the fitter said one of his rear shocks was leaking oil and cos they are a matched pair both would need re placement [very true] however my mate not knowing anything bout motors rang me for advice , and i thought hang on they fitted gas struts on your motor, not saying all garages play tricks,but it does happen. . . Ming