Mercedes Benz 2007 E320 BlueTec

My car is supposed to run only on the ultra low sulphur diesel. Because the gas station didn't have a clear sign, I accidentally filled the tank with low sulphur diesel, drove 1/10 of a mile to another station where there's ultra low sulphur diesel & want to have the low sulphur diesel removed & replaced with ultra low sulphur diesel. When I called the Mercedes 800#, I was told that I needed to have the car towed to the dealership & 'repaired' for $1000 (i.E, removing the low sulphur diesel & replacing w/the ultra low sulphur diesel won't work). I find this inconceivable, since I haven't even driven the car 1 mile. What's your advice? Thanks.