Manifold/header/muffler/tail Pipe problems of the 2015 Kia Motor Sedona

On 9/4/18, while driving on the parkway I noticed my car was sluggish & making a noise upon acceleration. I thought it was my muffler because I didnt have any warning lights illuminated on my dashboard to indicate a major problem. As I exited the parkway, my car stalled & I coasted to the side of the road. I was able to start it a couple more times before it died for good. I had the car towed to the neptune NJ kia where we authorized a $400 partial tear down of the engine which we thought was to diagnose the problem but it was only to take some pictures of the engine & oil filter for the warranty dept. We were then asked to provide maintenance records which we couldn't since my husband did the majority of work & we didn't think to keep receipts being that we'd never been in this situation with our other cars. We've been fighting this for a couple months now but our warranty has been denied for "lack of maintenance" as they stated we have sludge in our engine. However, this problem is bigger than my lack of receipts. Lack of receipts doesn't mean lack of maintenance! kia has a huge problem with their engines and they're using this technicality as a way to deny coverage even though their own 2015 warranty manual states "warranty coverage will not be denied solely because there is no record of maintenance. However, failures caused by lack of required maintenance are not covered by the warranty. " where's the proof we did anything wrong? to this day they still "dont know" what went wrong with my car as there were no fault codes pulled from my ecu & a full engine tear down was not done. Also, the dealer said they are now out of $7k long blocks for my car wonder why? and told me I'd have to go with a short block at a cost of $17k (extra parts & labor required) or figure out how to get an engine on my own. This is happening to too many people & needs to be addressed!.