Great choice Tony. I’ve ordered the same but from Sytner as they matched Marshalls offer. However, I didn’t order any extras as the packs were pointless for Q3. Now BMW have changed their configurator and are selling extras such as sunroof, Harman Sound speakers etc as stand alone.
Coming back to your question, I am aware some members were told £500 cashback along with 10% off on factory options with Marshalls. This was available at Q3 but since the cashback offer has continued until 31st Dec, I don’t see why the 10% shouldn’t continue and it’s the highest i’ve seen so far.
Another forum member called Vlad in Q3 received half price on the Harman Sound system option but that was for the Saloon. I’ll find you the thread. They messed around with his order so give it a try, you know the saying: If you don’t ask, you don’t get.
Have you enquired about any offers on extras yet?