Problems associated with White H7 Xenon HID Light Bulbs

I recently purchased a set of two White H7 Xenon HID Light Bulbs to replace the light bulbs that came with my 2004 treg. I didn't know how to install them myself and the Volkswagen dealership said they would do it for $30. When I took them in the mechanic said that they might melt the light housing and then I would have to replace the whole headlight unit!!!! The specs for the light bulb are Hyper White, 5000K Color Temperature and the Type/Volt/Watt:H7, 12V, 100W. Before I go installing them and possible damaging my vehicle, I was wondering if anyone else had installed bulbs such as these and had any problem with melting the housing or frying the electronic due to the hight wattage and voltage (both are double what the factory bulbs are).