Billing Automation System Finalization

Project Description
I am looking for a senior-level Make.com (Integromat) specialist to finalize and stress-test a critical billing automation for my brand. The engine is built, but it has logic "glitches" and webhook connection issues that need professional resolution.

The Goal
The system must automatically charge a customer for a CO2 refill the moment their return bottle is scanned "In Transit" by the carrier. It must work 100% of the time, regardless of the carrier (UPS, USPS, etc.) or slight variations in ShipStation data.

The Current Workflow
Trigger: ShipStation Webhook (V2) On New Track Event.

API Fetch: HTTP Module retrieves full shipment details using the tracking number.

Filter Logic: Validates that the shipment is a Return Label and is officially In Transit or Delivered.

Deduplication: Data Store check to ensure no double-billing occurs.

Shopify Search: Locates the customer/order based on the ShipStation payload.

Billing Execution: Validates the customer in Appstle Subscription App and triggers a billing attempt via API.

Required Deliverables
Rock-Solid Triggering: Fix the ShipStation Webhook so it fires reliably for every scan.

Carrier-Agnostic Filtering: Adjust the filter to handle different carrier status codes (e.g., some carriers might not send the exact string "transit").

Full Mapping Audit: Re-map all broken "pills" and variables caused by recent troubleshooting.

Comprehensive Error Handling: Add "Break" or "Ignore" directives so the scenario doesn't shut down if a single API call fails.

Full Testing Report: Demonstrate the scenario working across multiple test cases (different tracking numbers and statuses).

Requirements
Proven experience with ShipStation API and Shopify/Appstle API.

Advanced knowledge of HTTP modules (Auth, JSON parsing) in Make.com.

Ability to troubleshoot "silent failures" where data is blocked by filters.