The Westminster expenses watchdog has made fresh efforts to calm anger among MPs about the operation of the new system - including more face-to-face meetings.
Furious politicians condemned the Independent Parliamentary Standards Authority over its handling of new regulations brought in after last year's pay and perks scandal.
MPs' complaints will be revived on Wednesday morning in a Commons debate led by senior Labour backbencher David Winnick who attacked the "deeply bureaucratic and complex" system.
In an effort to head off mounting fury over its telephone hotline and email service, IPSA said it would introduce face-to-face surgeries from September.
A "liaison committee to aid communication" between officials and MPs is also to be set up and more time given for the repayment of advances of up to £4,000 for up-front costs.
That cash was offered last month amid complaints from MPs that they were being left out of pocket because of delays in paying claims for items such as stationery, hotel bills and travel.
IPSA's renewed efforts to smooth the waters come days after its operations director quit his job early saying he needed a break "for the sake of my health and sanity".
Chairman Sir Ian Kennedy told The Times that some MPs apologised for their treatment of IPSA staff and said he had been "surprised" at the hostility they had faced.
"I have been surprised at the level of noise, and to a degree the level of hostility, in some bordering on rudeness, from a small minority of MPs," he told the newspaper.
"It's not fair on staff and it's not what I would think the electorate regards as appropriate behaviour," he said.