Commonwealth Bank is experiencing fewer processing errors, fewer complaints and faster product development turnaround as a result of the implementation of its core banking platform. The head of the retail bank's transformation programme, Patricia Montague, said the volume of inquiries customers make on Monday morning about transactions over the weekend has gone down. People could now see what was going on in their accounts in much more detail.  They understood their balances better.  "For example, when they take cash out with a purchase at a store, their statement will break that down into two parts."The bank has reduced the number of core retail products from 16 to nine, but has increased the range of options available with each product. Montague said: "With our pensioner account, we used to have to change the account if the customer wanted access to a debit card. Now, the system allows us to issue a debit card with that account."Scheme debit is no longer a product. It is a feature that can be added to any product."This change is the result of what the bank calls COSSE - its customer offer sales and service engine. It is a tool that allows the bank to build products and campaigns very quickly. The core banking modernisation programme's director, Dave Curran, said the bank had changed the way it developed products. In the case of GoalSaver, a new bonus rate savings account, it selected a group of branches in Tasmania and tested the product before taking it to market. Curran said: "We looked at the response to pricing and the level of demand, and fed that live information into the development, whereas in the past we have had to rely assumptions."The bank also reported fewer customer calls resulting from batch processing delays, and better customer service as a result of fewer hand-offs and less reworking.Change of address is an example of a "once and done" activity on the new platform. It used to be passed to the back office for processing.