The CRUA/CVCA (2.0ll 110kw) have been around since 2013 I believe (maybe even 2012) on the 7 series in Europe. So in a way, the 2015 US version should have had the bugs worked out. Of course, the water pump issue has been known since 2013, so go figure.
Considering how much you are driving, you can certainly get away with long oil change interval.
At this point, it's more important to change the oil filter. Car is still running and doesn't burn oil, impressive!
I had the same thing and thought there could have a been a leak or something. When I did the timing belt, I did not find any leaking seals at all. So yes, i think it is just dirt collecting, from fuel spill, water pump drip, etc.
OK, I see your problem. The camshaft carrier is no longer aligned with the hole, right ?
Then just tighten the sprocket center bolt just enough so you can rotate the camshaft carrier back to the right place, then put the pin in and leave it there.
A pic would help understanding what you are saying.
And yes, if you didn't bend anything, you can take the sprocket off and put back, but you shouldn't have to do that.
also, if you are using the exact same belt, you should have been able to put on the new belt easily. not sure what the...
20V seems excessively high, double check with a volt meter to confirm it is actually putting out 20V on the battery. If indeed this is true (which I doubt), that battery will fry (overheat and leak) in very little time.
I'm sorry to hear your story. I am sure by now you realize the mechanic screwed up royally. I'm even surprised they have the balls to tell you the engine jumped time after they did a timing belt job!! Talk to them, they should own it. If they play games, you'll have to sue. sorry.