Perhaps the thermostat was only reachable after dismantling much of the cooling system? They probably followed the workshop manual.

Well, it would be Fn rude not to be eye wateringly thorough when its warranty work, wouldn't it.

Have to say that bears out my experience with that place, doesn't surprise me one bit, jack of all trades master of none. So many makers names on the sign outside they cannot be as good as a single-make specialist but stripping the engine before checking the obvious takes the biscuit even for them.

 

When you get it back, would be tempted to get it a once-over by somewhere you trust

 

At least you've got something half descent to thrash in the meanwhile 

I doubt they stripped the engine, what they probably said or meant to say, was they stripped down the front end, to gain better access to check for leaking hoses etc.

That said, it does seem to be taking ages to repair a fairly straight forward fault.

 

Logical approach would be.

1: Visual check for obvious leaks, leaking coolant stains the surrounding areas.

2: Sniffer test at expansion tank for combustion gasses. (Rules out head gasket or cracked head around the valve seats)

3: Check bulkhead gasket where coolant hoses mate to the heater matrix

4: If nothing found, suspect thermostat or water pump

Perhaps the thermostat was only reachable after dismantling much of the cooling system? They probably followed the workshop manual.

i do hope not!

Update on car ..

They fitted new thermostat.. took it for a test ride.. still overheating..

so now they have ordered a new water pump..

might get it back for the weekend

Oh dear.

I got my car back at lunch time, 

It was the water pump at fault, 

But I now have a new thermostat fitted also..

Sounds like you had a water pump from the same bad batch as me then. Glad they sorted it for you in the end!