The meeting was jointly organised by IT directors' forum Elite and user groups Imis and Socitm.
One user who attended the meeting this week said, "[Holloway] made it clear that the licensing charges were worldwide and he could not take any country-specific actions without clearance from the Microsoft hierarchy."
He did, however, promise a response within 48 hours.
Users have demanded an extension to the 1 October deadline for upgrading software and called on Microsoft to keep them better informed. One said, "We are looking for improvements in communications from Microsoft."
Microsoft confirmed that user concerns had been passed on but refused to discuss the details.
A Microsoft spokeswoman said, "The 48-hour commitment that Neil Holloway has made is to clarify certain specific questions that customers have raised regarding the current program."
Users also warned Microsoft that UK companies could end up paying £800m a year more as a result of the new licensing arrangements.