Mechanic Fixed wrong problem?

[Eiknujrac]

So I was pretty sure I had a bad head gasket the other day. There were bubbles along with oil in my coolant resevoir, and the coolant was extremely low. So I decide to see if I can find a leak, well to my suprise the first place I look ( the textbook area of head gasket failure on a m103 ) is the rear passenger side of the engine, and sure enough, there was fresh oil on the side of the block.

But I figure I would take it to a mechanic just to double check and make sure that's the problem before I rip the head off to change it, mostly because of my lack of free time.

So I get the car back today and see that they have changed the timing chain cover gasket? And said that was the cause of the leak?

What are the known symptoms of THAT gasket failure? And is there any other reason I would have oil/bubbles in my coolant and oil on the side of my bock?

Thanks alot

-E