Hello Ana,

Thanks for reaching out to us.

Please note that the official language of our support team is English, thus I would like to apologize in advance if anything is lost in the translation since we use Google Translate to translate your query.

You can use the extra option for a particular service. In each service setting, you have the option to add "Extra" for that particular service. This will add the option for the customers to select if they want to buy the extra service, but this comes in the form of duration and it is great to use if you want to add the option for the customer to choose the extra duration.

Unfortunately, it is not really appropriate to use if you want to offer a single product, in your case, a shampoo, since it offers extra duration, as previously mentioned. You can find more information regarding the Extras feature on this link.

Please feel free to search through our feature suggestion page,  to see if someone may have already suggested this feature. If you can't see it, feel free to add your suggestion there, and as more people vote, the feature will move higher on the priority list.

You can certainly follow our changeLog page if you'd like, where we state any changes/new features/bug fixes during updates and our newsletter, so you're informed about new features, bug fixes, freebies, etc.

I hope it helps. Please, let us know if you have any other questions.