IP Blacklisted by Zoho CRM

We use Zoho's API for integration between our back-end and Zoho CRM. However, it seems that our server's IP has been blocked.

I didn't get any notice from Zoho and have no idea why our IP has been black-listed. Last time this happened, we were down till Monday because Zoho Support is closed on Saturday and Sunday. Our business relies heavily on Zoho and Sunday is a working day for us so waiting till Monday will cost us a lot.

Any idea how to get the IP block removed without having to wait till Monday morning to speak personally to Zoho Support?