Ask for a courtesy car if they want to keep it all day. Usually these have to be booked 3ish weeks in advance.
Failing that, here.
https://www.motability.co.uk/get-support/if-something-happens/cars-wavs/replacement-travel
Motability doesn’t do a collection service. Some dealership offer picking up/dropping off the car, usually for a small fee, but that’s their offer, not MBs. MB, to my knowledge, also doesn’t reimburse Taxi rides, but i’m not 100% sure on that.
If your dealership sucks, go to another one. I never understood the fixation on a particular dealership – when we ordered our current car, we skipped the two closest dealerships after they turned funny when they realised it’s for a MB car, ordered it at the third 40 miles away.
In your case, i’d give Renault in Sheffield a ring, and schedule a service there – while straight away making clear that you need transportation if they want to keep the car all day/over night, or require the car being picked up/dropped off.
That all said:
Also, I very much doubt if there are any such things as “courtesy cars” available any more. You do have to pay.
Calling people out for “being misguided” while dropping this isn’t a great look.
For reference, we had a courtesy car when required. The only drawback was that we had to wait 2 weeks longer to the appointment as opposed to an appointment without requiring the courtesy car. We had a Taigo R-Line DSG when we had the steering rack replaced (from Thu-Mon) on the GTE. You of course have to put the fuel you use back in, but that goes without saying. That was 3 months ago.
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.