these are not ads and it's quite good that you have noticed this as we have just released it experimentally.
This is an integration with the leading event management system online: Eventbrite.
After a successful booking, the customer will be offered near future events close to the dropoff location. This is beneficial for you as a company because it's more likely that the customer will book your services to and from the event. Furthermore, because of the close integration with Eventbrite that we have done, after a customer buys a ticket for the event from your own booking form they will be redirected to the car booking form immediately where they can take care of the transportation from and to the event.
If you prefer not to show this integration on your booking form you can turn it off by going to your back office - Dashboard - Settings - Design settings - Show Upcoming Events: No.
Looking forward to receiving your feedback on the above.