2005 Mercruiser 5.0 in 237SD oil change

Does this engine have a split oil pan or some reason certified shops only get 1/2 of old oil out and then overfill engine by 2&1/2 qts. I told the last one (recently ) and they argued how they vacuumed all oil out and put 5qts in when I showed dip stick read way over . So I took it to local motel and drained 2&1/2 qts of nasty oil from low point hose (connected to hull water drain plug) which I told them about pre episode.
I only had one other certified shop when boat was brand new do same thing (only worse#another story). They said “just run it,it will go down” RRRWRONG ! Homey ain’t that stupid !  Bought new , 18 yrs old and Guess Who’ll change oil next ?