Duxbury said: "Their support in advancing a due payment to the club made sure we signed Alessandro ahead of rival clubs looking to secure his services. He promises to be a major addition to our squad, along with Manuel Da Costa, and I know Gianfranco is excited to be working with both of them.
"I must offer personal thanks to Executive Director Bill Mummery for the way he has endorsed what we are trying to achieve here."
Mummery said: "We stepped in to assist Scott and his team on the basis that the transfer window was coming to a close. We are very immersed with our strategic relations with West Ham and this was a good opportunity for us to demonstrate that support in a meaningful way and we were glad to do it."
And Zola added: "It's fantastic that they help sustain us. They believe in what we are doing and have given us their support. We are going to try everything possible to match that with what we are doing."