Reschedule calendar appointments with Google Sheets and Google Calendar

Quick overview This workflow is triggered by another n8n workflow to reschedule an existing appointment by looking up the current booking in Google Sheets, validating the requested new slot via a sub-workflow, and updating the event in Google Calendar with the new date/time and service details. How it works Receives appointment details (phone, current date/time, new date/time, and new service type) from another workflow. Looks up the existing booked appointment in Google Sheets using the phone number and the current (preferred) date and time. If a matching appointment is found, builds the new start and end timestamps for the requested slot. Calls a separate n8n workflow to check whether the requested new slot is available. If the slot is available, updates the corresponding Google Calendar event with the new start/end time, updated summary, and phone number in the description. Returns a structured result indicating success (Rescheduled=true plus formatted date/time) or failure with an error such as appointment_not_found, new_slot_unavailable, calendar_unavailable, or crm_unavailable. Setup Connect Google Sheets OAuth credentials and replace YOUR_GOOGLE_SHEET_ID with your spreadshee