Gelato: Print on Demand

I have been a Gelato customer for nearly a year with over $125,000 in sales this calendar year through their platform. Until recently, I have been largely happy with the service — product quality has been consistently good and the platform generally works well.
That makes my current experience all the more frustrating.
For several weeks I have been completely unable to publish new products to my Shopify store without performing a "Sync Products" action for every single product I attempt to add. I have contacted support at least six times, worked through every troubleshooting step suggested, and currently have open tickets with no resolution. The last two support representatives I communicated with stopped responding entirely and never followed up. Now, the situation has worsened — product sync now freezes at 1% and will not complete, leaving me fully blocked from both publishing and syncing my store.
I understand technical issues happen. What is not acceptable is weeks of silence, ghosted support agents, and open tickets going nowhere. New designs I cannot publish are revenue I cannot generate.
I am giving Gelato one final opportunity to resolve this before moving my fulfillment to another platform.