Engine Light - Replacing Catalytic Converter

I've had the engine light coming on (solid, not flashing) in my 2013 C-Max Energi and left it at the dealer yesterday. They called today and are replacing the catalytic converter.

They said they need the car for 3 or 4 days because they need to pull the engine to do the replacement. I have a loaner I can keep till it's done but it really seems strange that it's so hard to get to. They are a local Ford dealer, so I assume they know what they're doing.

Part of what bothers me is they didn't know going in what it would take. They seem to have discovered it after they got in and tried to remove the catalytic converter.

Anyone know if this sounds reasonable?

Thanks

Engine Light - Replacing Catalytic Converter