I would agree with Namrog84 (yes, I'm an MS employee). Also, the Excel UserVoice should allow you to report bugs and I would say should be your first stop for any issues that you encounter (https://excel.uservoice.com/).

Also, I worked as a Product Manager (Marketing) in the Office division for about 3 years, and honestly if you find folks who you know in Marketing, we're all about community and are willing to help get you the right resources and to the right people, regardless if it's our product that you're having trouble with.

Finally, I know for a fact that the marketing and engineering teams are actively engaged on StackOverflow, so if you were able to post something there, they will find it and respond.