I wonder if anybody could help I've been told my 2003 1.6 petrol has two catalytic converters one that bolts on to the manifold and one underneath is this correct as the garage has replaced the part that comes of the manifold and are now telling me the second cat is breaking up.

Yes, they have 2 as standard. One is just under the manifold, and the second is underneath the car.
Have they done this all as part as sorting one problem? could be that they were wrong the first time...???

Looks like they missed it first time round. Took the car in two weeks ago they replaced the front one must of missed the second one bit worrying a gasket didn't turn up so they they sealed it as best they could when they replaced the gasket they noticed the second cat was breaking up. Thanks for the answer I've had Mazda telling me it's got one a Mazda specialist telling me it has one never had a car with two cats why does it need two most cars run with one?