The controversy over charging for withdrawing money from cash machines will be aired in parliament today when an early day motion will attack the "greed" of financial firms and their scant regard for financial exclusion.
The issue has dogged the Link network since Barclays tried four months ago to introduce a £1 surcharge for other firms' customers using its machines.
Barclays, in the face of legal action from Nationwide, has yet to introduce the charge. It threatened to change the dynamics of Link, which had previously been offered free or worked on the basis of "disloyalty" fees levied by financial firms on their customers when they used others' machines.
Barclays has scrapped its disloyalty fee at a cost of £2m a month, and wants to recoup some of this via the surcharge on other banks' customers.
Nationwide, the loudest opponent of the £1 fee, yesterday produced research showing that 91% of the public do not believe they should be surcharged for withdrawing their own money.
If surcharges were introduced, the NOP poll for Nationwide found that only 7% of people would carry on using the surcharging machines.
David Chidgey, Liberal Democrat MP for Eastleigh, said his early day motion would attempt to draw attention to the different approach to charging between banks and building societies - some of which continue to offer free access to the Link network.