I do hope you are right and that it's fixed however the way you are being passed about when trying to reject feels very familiar. You may want to read this and see what happened when I tried to reject a car
http://mynewmercedesbenzrattles.wordpress.com/
Whilst legally BMW FS and BMW UK are 2 different entities you will find that they are sitting in the same office and don't behave as such.
And finally remember that under the sale of goods act, it is the dealer that sold you the car and it would be them that you took to court if it ever got that far (although the finance company could be held jointly liable)
KEEP A DIARY of all calls, emails etc