Scheme debit is all out of puff in Australia at present, a briefly dynamic mover in the payments space that's had all its momentum cut away.The market share for scheme debit peaked at 28.6 per cent in March 2010. This market share fell in three of the last four months, including in July. The market share of scheme debit is now 26.6 per cent.The loss of two percentage points in market share is largely Woolworths' doing, and representative of a payments landscape that may be shifting more than is usual.Woolworths decided in April that it would reroute all debit card payments originating in its supermarkets and other outlets for processing along the Eftpos network used for all other bank-issued debit cards in Australia.For Woolworths' customers the shift in approach cost them the option of pressing the "credit" button on the payment terminal, which is what building societies and credit unions and more recently banks have coached customers with scheme debit cards to do.The customer has had to make do with a (largely redundant) choice between the savings and cheque payment buttons on the terminal.Banks have pushed scheme debit cards aggressively over the past two years, chasing payment flows and profits that work out more favourably than they would if the same customers were still using 1980s style Eftpos and ATM cards.This trend does not suit Woolworths, which developed its own payment switch over recent years to give it more options, and to lower costs, in the payments chain on which it so critically depends.The redirection of scheme debit payments took effect in April and with only two weeks notice to customers and their banks.For any customer obliged to sign the merchant receipt - since they simply did not have PIN numbers - Woolworths offered no service. This cohort - mostly long serving customers of tiny credit unions - have been turned away from Woolworths and to other merchants such as Coles and IGA.Practically all credit union and building society customers, however, suffer at the hands of Woolworths, since in many cases pressing the savings button means that they pay fees.Before April few credit union customers incurred fees from shopping at Woolworths because they followed the advice of their credit union and pressed credit for what was a debit transaction.Now many pay fees in the form of excess transaction fees charged at the end of the month. One way to avoid this is to avoid Woolworths.The other option is to shop mostly at Woolworths and get cash out from them, a choice that helps Woolworths both in actual shopping and the higher fee that the banks pay them for a cash-out transaction.Outdated pricing on most basic transaction accounts of small banks is part of the problem, as is the lack of PINs for some customers.The savings to Woolworths are around $500,000, a choice that lowers costs and also lowers the quality of customer service.Critical to Woolworths' thinking is that the payment flows between banks and retailers are reversed under this approach.