Okay, but it is absolutely a bug because the in-game description doesn't suggest any sort of re-roll or time pressures or anything like you mentioned, it just says you get a 25% boost to the commission rate, meaning that $4k I should have gotten should have gone up by a few hundred dollars rather than down several thousand, especially considering I fucked the dude I was doing business with.
You
are getting a boost to the commission rate though, you simply failed to sell as many as you previously had the chance to.
Say you have a base rate of 16% commission, and you had a lucky phone call, where the person on the other end representing a company of 20 employees decides to buy 40 pills, you'll make 16% of 40, i.e. 6.4x whatever value it is for that pill if you take that deal. If you opt instead to do a demonstration of the product and only sell the normally expected 20 pills as a result, you end up with 20% of 20, i.e. 4x the pill value. You still got a bigger rate in this case (20% as opposed to 16%) despite earning 2.4x the pill's value less than you could have had you taken the deal originally offered.
Is this realistic? I think so, you've given them a chance to re-evaluate overnight (or longer depending on how soon you schedule it), they may have had a meeting about it internally since, and the person you do the demo for may not even be the person you spoke to on the phone. Assuming this is intended, as I believe it probably is, perhaps the wording of the demo description could be made clearer to indicate that this is effectively a gamble (beyond the possibility of messing up the demo itself) to avoid confusion.