I see it’s been a while, but I’d suggest checking with your local auto parts stores or online retailers that specialize in car parts. They might have the toggle button you're looking for, so you don't have to buy a whole new master window switch. When it comes to replacing and removing the switch, I'd recommend looking up some video tutorials on platforms like YouTube. You can find some handy guides that demonstrate the process step by step. By the way, while you're at it, you should also consider getting the best baby car sun shades for your GLC300. They're a lifesaver when it comes to keeping the passengers protected from the sun's rays. Just thought I'd throw that in since it's always great to multitask and take care of multiple car needs at once.