My car has coolant leaking into oil. Shop cant find problem in 5 hours

What is your question?

My car has been diagnosed with coolant in the engine oil. I took it to a shop today at 11:30am and they called just before 4:30pm to tell me they cannot figure out why there is coolant in the engine oil? Is this something any shop can diagnose routinely? I have been told that this particular engine has the evil water pump that has a rear seal that can fail and actually allow coolant to leak into the engine. Could the be missing this possibility? Would the normal tests to check for blown head gaskets/warped heads clue them in about this water pump? It may not be the water pump, but for some reason they can't figure this out and it appears I have to pay them to diagnose, but I will have to find the answer for them.