He noted the company also employed about 100 non-union drivers.
He similarly denied a claim by an anonymous correspondent in email to the Herald that negotiations had broken down, but acknowledged there was a considerable gap between the parties.
Mr Froggatt said further industrial action was possible, but that would not be before Christmas and would depend on instructions from union members at the meeting.
He said the unions were seeking a 2.95 per cent pay rise on hourly rates now starting at $16.37c for new drivers and rising to $20.40c after nine months.
That compared with what he said was an offer of 0.75 per cent from the company, which is Auckland's largest bus operator by far.
Another big point of difference was on working hours, after controversial roster changes by the company in July which put most drivers on rotating shifts.
The unions, which are challenging the changes before the Employment Relations Authority, want a mixture of rotating and non-rotating shifts and a reduction of the daily maximum span of working hours from 13 to 12.
Mr Froggatt said the effect of the roster changes had been dramatic.
"It has disrupted the lifestyles of a lot of people - it doesn't suit them, they're all upset and they want some changes," he said.
NZ Bus northern operations manager Shane McMahon said he needed to work with Mr Froggatt through arrangements for December 22 before indicating what services could be kept running.
"It will probably be two days before we will have locked it down," he said.
"It's premature to say what we're doing because we're just working through some options with them [the unions]."
Mr McMahon would not comment on differences between the parties, saying "we're right at the early stage of bargaining.
"It's not a good look [to comment] - it's not respectful to the other side."