Not online yet. Contact the campsite and they'll sort it.
There's no self-service way to change a booking yet, so contact the campsite directly and quote your booking reference. Depending on the change they may amend the booking at their end or rebook you on new dates.
For date changes it's worth getting in touch early, especially in high season, so the campsite can check availability first.
Email support@pillowcase.io with your campsite name or booking reference and we'll pick it up from there.