Disintegrated Oil Pump

The oil pump in my 2012 Volt disintegrated suddenly without any prior warning just one month out of power train warranty.

GM is not helping me to fix this because I bought the car pre-owned (so, no Good Will warranty even though I have maintained the car as recommended and the prior owner's maintenance records are in the glove box. I spoke with GM customer service and the Electric Vehicle team and all said the same as the dealer service manager: I am out of luck as per GM policy).

So, I spent $2500 to have the oil pump replaced (at a Chevy dealer) and the car ran fine for about a week. Now it's making a tapping/clicking noise and the Knock Sensor error (P0324) has triggered the CEL.

Anyone else have an oil pump disintegrate? I am planning to file a report with the NHTSA so that there is some oversight. But, I am curious if there are any other cases of oil pumps disintegrating like the one in my car did.

Thoughts on what the tapping might be now? It is full of oil and the oil is clean.

TIA!