Your Santa Fe is covered by the manufacturer's 5 year unlimited mileage warranty. Have you taken it to your Hyundai dealer to get it fixed? It sounds like an electrics problem which should show up a fault code if your car is plugged into the HyScan diagnostics equipment. You are most welcome to call my workshop foreman, Ian Bonthron, for advice.
Patrick Stone
Premier Autocentres
184-214 Blackfen Road
Sidcup
Kent
DA15 8PT
Tel: 020 8850 0066
Web: www.123premier.com
Patrick Stone, November 2008