My F30 328i normalizes at 205 (right in the middle of 160 and 250) 99% of the time. It might climb to 220 or so on a really hot day and going up a really long hill. It has never hit 250.
You definitely need to take it in again ASAP. If it's a long distance to the dealer, I wouldn't drive it there, I'd have them put your car on a truck.