is my dealership ripping me off, they want 300.00 for 15000 service, i just had

Its hard to say if they are ripping you off or not, because we don't know for $300 what you are getting. You'll need to pull out your owners manual and see what Kia reccomends for a 15,000 mile service. If there is some sort of adjustment or procedure that is required, it could justify the price. If its just an oil change and tire rotation, then yeah, its high!

GET A COMPLETE LIST OF WORK AND POST SO WE CAN ADVISE