Try the EV breakers up North first but if that doesn't work...
Random info from Wikipedia:
1.
SAIC, the parent company of MG5 has a business relationship with Volkswagen in China called, guess what,
SAIC Volkswagen. A quick look suggests SAIC just makes VW cars in China under licence but it may be possible that VW parts fit MGs? I dunno.
2. The European MG5 EV is known as the
Roewe Ei5 in China. The
Roewe i5 is also a petrol/hybrid
If he does goes shopping on Aliexpress etc, he's more likely to find a Roewe part rather than a MG5 which was only sold in Europe.
Random thought - maybe pop into 24hr mechanics or Bobo motors. Didn't they buy/sell/rent a lot of MG5 taxis? RC's database might list the biggest owners of MG taxis? Maybe they have a line on a supplier or they might do the repair themselves?