Engine died kia wants 5000

I did not get any signal engine needed oil and I forgot to change itin a year 2015 Sedona kia. 17,000 miles. now kia wants 5000 because I did not maintain the vehicle under lease rules. but can no oil change for a year ruin the engine. could it be a lemon, how can I prove this, they said it needs a new engine cause I did not get an oil change. im a woman feel like im getting screwed