NHTSA Complaint #11458784 — 2021 KIA SELTOS

My 2021 Kia Seltos lost pick up pulling out of parking lot at work. Limped it to a parking lot and had it towed to Kia. Spoke to service guy at Kia dealership today. He claims that my oil was low and dirty and needs to be changed every 4000 miles (manual says 7500). I told him this and he said thats only if I use full synthetic...says it on the sticker in window and receipt. Full synthetic was used. They will change the oil but they feel its an engine issue and since the shop that did my oil change did something wrong (according to them), it wont be covered by warranty. This is a 2021 with about 11000 miles. Oil change was done about 4500 miles ago. He claims that my warranty would not cover this due to low oil. Oh and not one warning light came on. NO OIL LIGHT, NO CHECK ENGINE LIGHT. I was reading about a recall that I never got a recall letter on because according to VIN # my car isn't included regarding improperly heat treated piston oil rings that causes engine damage and excessive oil consumption. Sounds like exactly what is going on with my car. I certainly cant afford a new engine out of pocket and don't believe I did anything that my warranty should be voided over. I need help!