@Lisa990 I think your best solution here will proceed from the reaction you get in your correspondence.
But in general, I would not recommend ever conducting a transaction in the manner you did again. Be straightforward and consistent about your prices, including Extra Guest Fees, and stick to them - even if it means losing a prospective guest who's hunting for a discount. And under no circumstances offer a conditional after-the-stay rebate: that's nothing but a setup for conflict.
You've seen how messy it gets when you try fiddling with pricing after a request - that's not just you, it's also the many glitches in Airbnb's booking alteration template. So when you're having a slow stretch and want to try discounts, do it in your calendar so it's already locked in when the guest requests to book. Price changes after the point of sale are bound to end badly.