Dealership Voiding My Warranty For An Aftermarket Oil Filter

Location: Chicago

Long story short, I took my car into the dealership today because I got a message saying reduced engine power. I called the dealership scheduled an appointment to get it diagnosed. I have a 30,000 mile bumper to bumper warranty and I’m currently sitting at about 22,xxx miles. After a few hours they returned my call stating the issue was with the engine flow oil control valve and that I would need to replace the oil valve, oil, oil filter and oil pan as well as the seal to reseal the oil pan. They also let me know that because I had an aftermarket oil filter. The whole charge would be applied to me and I would have to pay out-of-pocket and my warranty was voided because of an aftermarket oil filter and not a Chevy oil filter. I have a video of the service tech stating he didn’t know for sure but the issue could be caused by the last oil change but he wasn’t sure. Never an exact claim stating it was caused by the oil filter. The parts totaled to about roughly $480 however the full charge was $1147. I understand labor is not free or cheap, but I don’t have that kind of money at the moment so I told them I would have to refuse for now. I figured I would park my car in my garage and walk to work for the meantime until I have enough money to replace the part because I live pretty close to my Job. The service advisor then said that he would be charging me a out of warranty diagnostic which came out to $199.95 + a $20 shop charge for a total of $220.00. Do they have grounds to do this? I really don’t want to pay for the diagnostic as I’m still under warranty and under the magnusson moss act I am entitled to use 3rd party products and it shouldn’t void my warranty as it did not cause the issue directly. I’ve taken my car in before last month for a issue with the camera and they replace it no problem.