i know in advance, ill get jumped on, but here goes.
any shop that allows and accepts a customer self diagnosed problem to be repaired without a proper diagnostic check deserves having its repair procedures questioned, as well as their workmanship.
like reagan said, trust but verify. there are a variety of ways to end up with a big puddle of coolant on the ground without it being a water pump. several holes in the radiator comes to mind.
you leave yourself open to a lot of criticism when the repair fails to fix the problem, or causes another to pop up. i know there are times that one repair begats another on older coaches, but there are too many parts put on this coach to have the major failure described here. it doesnt appear that the water pump and the oil leak are related, so something was missed or incorrectly diagnosed,or the story is missing major sections of explanation. this is most often the case.
unless there is some very apparent reason which i dont see, the shop has no liability. they did what the owner requested. its up to the owner to prove the shop did something wrong.
like i said, if you or your shop doesnt personally do a diagnosis, and start throwing parts at a problem, you end up with stories like this.
to the owner, if you leave home with an older coach, or any coach for that matter, you had better either have had it checked over and pronounced good to go, and be mechanically inclined enough to take care of it yourself, or have a fat wallet. on the road repairs can get very expensive.