The Ford dealership have a system they can look up part numbers on, they are just being lazy.
If you give them the registration of another car, which already has halogen clusters with LED DRLs (so a Zetec S or a Zetec/Titanium with AP1), then it makes it easier to find the part number on their system as it will only show what is fitted to that car and not all the options available.
Either that or get them from someone else. Fordpartsuk are good, they will quote them for you, just based on your reg and the description of the part. Just make sure you say the halogen cluster LED DRL headlights from the appearance pack, not the xenons.