Garage supplied me with a courtesy car after ferrying my partner back and forth to work for 3 days. Drove the MG to garage.
Tony - Just keep a rough mental note of the cost / expense & time that this takes before this is finally resolved, then request the price of the coil spring and the time allowed to install the spring ( about one hour I think ) then compare back to back !.
I predict that after only one week, the cost of not having the problem rectified will be more than the cost of the repair.
Let's just make a pure guess had the affected part been available in stock.
Cost of the road spring, pure ball park figure ????? ..... £50 ( ish ) ?.
Estimated labour charge to install ????? ................. Approx one hour ????........ £100 - 150 ( ish ).
Job sorted at a single appointment, little inconvenience to the dealer or customer and off we go.
Set against, the wait time for a single £50 item.
For EVERY week(s) car hire ......... between £400 - 500 ?

.
Let's keep our fingers firmly crossed ?and say it arrives in two weeks ( remember it's coming on boat from China folks ).
Cost of repair is now is a conservative £800 in car hire and £150 ( ish ) in parts & labour.
Two week wait for the dealer and the customer and a cost close to £1,000 vs £150.00 had the part been available ??.
Multiply this by the number of cars awaiting parts and it is simply not a sustainable option in any business.
If we needed any further evidence of this type of repeated action, we only need to look at the recent shortage of interior door handles on MG4 & ZS EV face lift, steering column assemblies on ZS EV and now rear road springs shortages on the ZS EV facelift.
As MG increases production of both current models and then introduces new models, the supply of replacement parts has to increase inline, otherwise dealers are going to become overwhelmed with broken cars all awaiting spare parts !.