Car dealer made a mistake

[admin]

My 1999 Montero which has been very well taken care of and maintained was recently in for an oil change. 2 days later blue smoke came out of the exhaust pipe and the engine was running rough. When I checked the oil I found the dealer had put in to much oil, roughly 1 1/2 quarts to much. The next thing I noticed is the oil pressure guage is reading 0 PSI or no oil pressure at all. How do I get the dealer to own up to his mistake??

Any input is greatly appreciated.