They also believe the organisation has saved more than £450,000 in wages over the 62 days, while janitors have lost £77 in wages of every strike day.
However, the authority disputes this, claiming the workers are being supported by union strike pay of around £70 per day.
"There's no need for his strike to continue.
"There's a very good offer on the table.
"Where in today's world can you find union leaders rejecting an offer for their members that guarantees jobs and a pay hike of anything between £1,200 and £4,000, and a shorter week? 
"You have to shake your head; you could not make this up."
The latest two week strike was launched this week.