Retrieve prompt for slot fulfillment from Webhook Response

[VoiceWorx Ai]

Hi,

The bot we have has multiple slots and is enabled for Webhook for slot fulfillment. After fetching value for one slot, we require that the the prompt for the next slot is set dynamically. But, dialogflow picks the prompt for next slot from the intent design. 

I've attached details along with the response that we are sending vs the response we are getting. 

Kindly let us know of what we are missing here.