You can communicate with the client directly via the Client discussion board at the bottom of the project page:

Whenever you have questions about the project's context or need the deadline to be extended, the Client discussion board is your go-to tool.

While communicating with clients, keep in mind:

• Treat clients respectfully and professionally, regardless of how they behave.
• Negotiating prices with clients is strictly forbidden.
• Sharing personal contact information or communicating outside the BLEND platform is a violation of BLEND’s Terms of Service and can result in warnings and/or account suspension.