I had the same problem with the old handbrake lever and an adaption that presses the button to release the brake and that adaption hitting the gear shift knob but lucky for myself it turned out I didn’t need the lever.
I thought Motability were getting more involved when it came to adaptions because on my current order they put a pulse on it because of the said hand-brake adaption I haven’t had in my previous 5 MB cars.
I had my installer on email and phone not to mention MB themselves nagging me to get the adaption I’ve never had and told them countless times with this being my sixth Motability car I know what adaptions I need, trust me. They relented in the end after they got their feet out of their mouths.
There’s piece of mind and there’s antagonising but my advice for H.K_R is to contact the installer and if you don’t know who they are the dealer should because there the ones who put through the order in the first place. My installers have a mobile unit that comes to me, only used it once but something to think about if you can’t get to them.