@Sarika9
I guess you have to decide to pursue the extra guest fee.
I notice you allow for 7 guests with your basic listing price and it is only from 8 on that extra guest fees apply. How many extra guests were involved here and did that number fall within your basic 7?
Sarika, they may agree to a prompt review but that is improbable, if they did sneak in additional guests there is a possibility they may wish to drag it out if they think (or you give them an indication) a claim might come from you, or they might not review you at all. They will do this because they will be aware, the longer it is before you lodge a payment claim, the less likely Airbnb are going to want to be involved with it!
But I would be pleasant, say nothing to them to get them offside, you will probably get a good review, but mention the disregard for your house-rules in your review. Once the reviews are published, you are right they can't hurt you.
If it were me I would let it go for the time unless there are other issues involved, let them give you a great review, and once the review window has closed, report them for breaking your house-rules and defrauding both you and Airbnb!
Airbnb don't take kindly to others 'cutting their lunch' and they might be more inclined to chase the guest for an additional payment, despite the time delay if they think they have been duded by the guest!
I can see why some guests would be tempted to do this Sarika, $2,000 per night is a substantial tariff and coupled with a 3 night minimum stay means the very least a guest will pay you is getting up towards $10,000, which is not an insignificant amount of money. The guest is going to think, "We have already paid them enough, another guest or two is no big deal"!
Cheers........Rob