Same problem with my 2013 Terrain.
It was cold out, 2*F, yesterday 1/21/2019, while exiting the highway, it stalled on the exit ramp. My wife was able to restart it, it was running rough. She got to her destination, and noticed oil was leaking from it. Upon having it towed to our mechanic, he determined that the rear main seal failed. Upon him researching the possible causes, he came up with the same service bulletin 14882, and advised my wife to call GM with this information. She called, and was told "I can not find that service bulletin", but she was working at that time, so she left it at that. I called GM this morning and talked to the same person. He told me that the VIN doesn't match that bulletin. I asked why not, and he said it wasn't manufactured at the right facility to qualify for the bulletin.
Not satisfied with that, I called a different number and talked to a different person, which was more helpful and polite, but was told the same thing. I was informed that these engines are manufactured at different facilities with parts from different sources, that's why only certain vehicles are covered. He went on to say "Save all your receipts, and your case number, because in a few years from now your vehicle might be added to this bulletin. And at that time, if the repair was done by our guidelines, you may be reimbursed then."
I have filled out a form with the U.S. Dot National Highway Traffic Safety Administration, letting them know what GM is up to. Our plan of action is to get it repaired and trade it in ASAP. We've been loyal GM owners since 1990, having owned 11 different GM vehicles over these 29 years, it saddens me to say that this will be my last GM. They know that these engines are having issues with burning oil at a high rate, and the PVC system failures, why doesn't GM just bite the bullet now, and include more vehicles? It's all about the all mighty dollar, that's why.