Well done Carlmelia. I've had similar frustrations at 'peeling back the onion skin' to get past the reticence and belligerence of the outer layers of MINI management. And, I agree, it isn't pleasant.
Citizen's Advice Bureau were brilliant! They outlined my rights and suggested that I was 'minded' to give the dealer three attempts to resolve my thermostat issues within a reasonable time of 2 weeks before starting formal rejection proceedings.
Only at dealer-principle level was there any real concern to resolve my issues, so my advice will always be to escalate the problem into his/her area asap. It took me 6-7 months to find this out, though...
Feel empowered to 'name + shame'?