Urgent Debugging: AI Booking System Integration

Job ID: 40470677

Budget: $250 – $750 USD

Make.com + GoHighLevel + Retell AI integration — debug appointment booking scenario (urgent)

I'm building an AI voice receptionist for a landscaping company using Retell AI (voice agent), Make.com (automation), and GoHighLevel (CRM + calendar). The system needs to handle two flows triggered by webhook from Retell: (1) check calendar availability, (2) book appointment with SMS/email confirmation.

Current status: Both Make scenarios are built but failing intermittently. I've resolved several issues already (date format, version header, API token rotation), but the booking scenario still returns errors and I need an expert to do a full audit and stabilize the system.

Stack:

- Retell AI voice agent (custom prompt, end_call function configured)
- Make.com (2 scenarios: S1 Check Availability, S2 Booking Appointment + Email)
- GoHighLevel (Private Integration API, Calendar, Contacts, Conversations)
- Gmail module for confirmation emails

What I need:

1. Audit both Make scenarios end-to-end and fix all remaining errors
2. Verify GHL API calls (headers, scopes, payload structure for /calendars/free-slots and /calendars/events/appointments)
3. Confirm timezone handling (America/Los_Angeles), Tuesday/Thursday-only availability, 30-day search window
4. Test the full flow with a Retell test call until it works reliably
5. Brief written handover so I can maintain it

Deliverables: Working end-to-end booking flow + short Loom video walking me through what you changed and why.

Important:

- I will give you temporary access to Make and GHL (no credentials shared on this platform)
- I need someone who has already worked with the GHL API v2 (the Version: 2021-07-28 header, Private Integration tokens, calendar endpoints) — please confirm this experience in your bid
- French or English both fine

Budget: $200-400 fixed price, depending on scope after initial review

Timeline: Need it stabilized within 3-5 days

To apply, please answer briefly:

Have you integrated Make.com with GoHighLevel API v2 before? Which endpoints?

Have you worked with Retell AI webhooks?

Estimated hours to complete?