If you need to change the service type, we recommend you cancel and create a fresh booking.

Eg. You accidentally booked house sitting, but now you want to book pet sitting, you would cancel the booking and create a fresh booking with the service type you need. 

Note: If you can't book a particular Sitter for a service type you want, it probably means they don't offer it. So you'll need to use the advanced search filters to find a Sitter that does. Or, post a job.