I’m fairly confident this isn’t a troll because I too drove a new Corsa the other week (courtesy car whilst the MG4 was in for repairs) and it is indeed horrendous beyond belief. “How could anyone buy this” is exactly what I thought, so OP is posting the truth in respect of that at least.
I do sympathise with you. The MG4 is naff. If you’re used to good cars, particularly driver focused cars, it’s sad coming to an MG4 and very frustrating. But… you did choose the base SE so if you’re a keen driver, what did you expect???
That said, it’s not supposed to be a ‘good’ car. It’s supposed to be a cheap car. And it is. It’s is a very very good ‘cheap’ car, so it hits its main (and only) purpose exceptionally well.
I’ve found that software updates make a night and day difference with a lot of issues. If yours is still not right, check the latest software update has actually been applied.
Sounds like you’ve got a faulty example which is a crap position to be in. You should have been able to reject the car or at least get warranty work done by now, unless the issues only arose way after cooling off period ended.
Like others had said, try an early termination and walk away from MG (and all Chinese EVs to benefit your own mental health) and get a more proven brand. As a ‘petrol head’ I have to confess that EVs are better in every way, unless you’re wanting performance and ‘fun’ - if you’ve got an SE I’m guessing not, so don’t run from EVs.
You can get a used FSH polestar2, Tesla M3, Kona, Niro, Born, EV6, Ioniq5 (to name a few) for about £10k less than a new MG4 or MGS5 - you’d be insane to choose a brand new MG over any of these.
MG is crap, but you get what you pay for and you should’ve stomped your feet to get shut of the car sooner. Terminate the agreement.