Good question. I'm not sure, and I'm not an English language graduate.
A quick Google search shows that "you and your company's", "your and your company's" and "yours and your company's" are all being used very commonly. This confirms that even English-speaking people get confused about this rule.
I would use the following: "In order not to waste you and your company's time, etc."
In that sentence, "you and your company" are put in one single basket, and share "the same time". If you say "your and your company's", it means that time is not shared...