I need some serious help!!!!

ghead
I bought my dream 1995 dakar M3 about a year and a half ago for $12k, 123k miles; well equipped with lots of AC Schnitzer goodies from the 18" wheels to the spoilers, shifter knob, race pedals, H&R suspension, etc. A dream come true after having owned a 318i. Bought the M3 on a whim without thinking much or having it inspected... Have been looking for a yellow 95 for many years in my area (san diego).
Just at the end of last year I took in to fix a head gasket leak which lead to having them machine the head and then it turned out that the short block was warped and needed to be machined... so about $6k later and two oil pans; it is still leaking from the short block (my guess, mechanic keeps blaming the oil pan) and I have just about had it with my mechanic.
So any kind of help would be great...
I am short of sueing the mechanic for making the little problem into a huge headache for me.
I did get a second opinion from another mechanic but it looks like even though they call themselves "bimmer specialist" they do not know M3's.
Thanks in advance to anyone who can help!!!