Sorry to hear about your added expenditure! You should be able to cancel your Hyundai extended warranty and get a full refund if you do so within 60 days of the purchase of the warranty. To cancel your warranty, you can either call or visit the dealership where you purchased the warranty or call Hyundai automotive warranty services at 1-800-621-2130.
If you cancel the warranty after the 60-day period, the dealership may prorate the warranty and give you a reimbursement, but you should check with them to make sure. If you can’t get a refund, there’s no reason to cancel your extended warranty.