This is a simple one. If your hair looks orange, it means you had a very warm or orange base to begin with and prior to application. Caramel is formulated with a gold tone. The product is designed for use on very light or bleached blonde hair. With such light bases, you can only go to a deeper blonde by using a gold undertone colourant, unless you firstly pre-pigment with a pure gold. If a colourant that was merely depth (so no tone) was applied to bleached hair, the result would be green tinged. However, if someone has lightened dark hair to a gingery-auburn or very peachy blonde colour, then attempt to use Caramel, there is already an abundant level of gold in that hair, therefore the gold tone in Caramel has nothing to fill and can only display.
If your hair looks very orange after using Caramel, the indicator is the base shade was too dark and warm to effectively display the colour. The easiest solution is for you to apply a standard no ammonia tone on tone colourant in a flat base 7.0 medium blonde to the hair. With an underlying gold base present, the use of this flat neutral colour would create a Caramel shade.