Joe's talk seems more directed towards saving business with Propmore Corporation. Even if Don assumes that whatever Joe is saying is true, still the code of conduct has been violated. Don must disregard facts present by Joe because it is not putting the victim in perspective.
The formal supervisor's note in the file can not act as a proof of how Jane historically has been. Even if we admit it as a proof, this must not have any bearing on the current case which is completely disconnected temporally from the past case. The prior conduct of Jane is of no consequence. So it should not affect Don's investigation in any way.
Don should give Jane some time to think over and discuss later how she sees the things in new light. If Jane's willing, a meeting between Jane and Bill could be organized in presence of Don and facts could be verified and that could be a real ice breaker. Meeting or without it, Don must try to communicate to Jane about what Bill said of his conduct. He should try to establish from Jane that the advances made by Bill were indeed unwarranted.
In final discussion with Jane, Don should record her statement in written and make her aware of her accountability of what she has said. Finally, if Jane still insists on going ahead, Don should propose to Jane that the company is willing to communicate to AirGoods Corporation that Bill as a sales representative is unacceptable to them. Further, Don should officially communicate to Joe of AirGoods corporation about Bill's conduct and ask them investigate as Bill is not an employee of Propmore.
If the investigations vindicate Jane's statements then AirGoods corporation must take action against Bill. This does not mean that Propmore needs to end business with AirGoods, but if AirGoods fails to act, then the business dealings should be given a rethink according to company's guidelines.
If even sufficient investigation fails to prove Jane's allegations,...