Over the weekend, ANZ confirmed that it ceased development work on Mambo, though it will continue to meet funding commitments to BPay.National Australia Bank made a similar decision two months ago.Talk in payments circles suggests that Westpac management is also reviewing its participation in the project.Mambo was first conceived in 2006 as a solution to the growing demand by customers for more effective payment options. Banks committed to the project in late 2008, with the work being coordinated through Cardlink Services and BPay.BPay selected CSC as systems integrator and Tibco as supplier of the messaging software, with much detailed design work still being undertaken by CSC. Mambo, should it ever get off the ground, would provide one means of updating the present arrangements for bank transfers. These include the direct entry system for periodic payments and the 'pay anyone' feature supplied by internet banking services that piggy-back on that system.While previously supported by all major bank CEOs, and the ABA, Mambo has always been seen as an initiative of CBA and, to a lesser extent, Westpac, with ANZ and NAB being dragged into cooperating on the project.A willingness to pay shared development costs on a project that two of the Big Four banks are no longer assisting on is a costly one.Eighteen months ago, Bpay estimated the development budget for the project at around A$150 million, with the combined project said to be closer to $200 million.