Thank you for your responses. I should have been back on before now but forgot all about it.

Carlos50, whereabouts in the engine is that situated?

The car is going back in on Monday to have some bits done they couldn't do last time, this reservoir included, so just want to be sure I haven't got one before I give them both barrels!!

TDV6 Underbonnet

Fifth Horseman

Thank you very much for your comprehensive information. You have no idea how helpful you have been.
I’m very disappointed that a main dealer garage has flagged up, discussed and quoted for a job involving the dynamic response reservoir, a part my car clearly does not have!
Harwoods want £392 to replace the filter in my dynamic response reservoir that I don’t actually have in the 3 litre car. Not sure how to play it now......! What a terrible thing to do.
It wasn’t a mistake either, as I asked them to explain what this part was and why it needed replacing. Who ever did the Visual Health Check has added this under the miscellaneous heading, so the recommendation wasn’t on a list as standard and had to be added in manually 😡😡.

Regardless of the fact it is not applicable to your vehicle, £392 seems awfully expensive when the reservoir/filter (LR072550) costs just under £100..
For vehicles with it fitted its a 5year/80,000mile service item.

With this level of deceit/incompetence from the dealer even if they provide a very good apology I'd be tempted to flag this up to the local trading standards office.