H S I Issue

The H S I is inaccurate. When one presses the light button to bring up nearest and activates this,  the blue arrow depicting nearest is accurate but the H S I is totally inaccurate. Checked with my Garmin 760. This issue ongoing for months and Garmin Europe totally unable to help. Any setting changes merely changes the compass and has no effect on H S I. Latest software downloaded. Could forum members test their devices please? 

Paul