The control room was expected to be operational by 2007
Further delays to the South West's new fire control centre will push the cost up by nearly £1.6m, the Fire Brigades Union (FBU) has said.
A national network of nine regional fire control centres is proposed to replace 46 existing control rooms.
The union says the government is about to announce fresh delays of 10 months.
A spokesperson for Communities and Local Government declined to comment directly on the union's claims of increased cost and delays.
However, a spokeswoman said: "We are confident that the Fire Control system can be delivered."
The Taunton control room will cover Gloucestershire, Wiltshire, the greater Bristol area, Somerset, Dorset, Devon and Cornwall.
She added: "The Department's focus is making sure the benefits of this project are delivered to the fire and rescue service and the public."
The national £1.4bn project was meant to be finished by 2007 and save so much money it would pay for itself in five years.
A series of delays followed by further major technical problems has seen the completion date pushed back,with the FBU claiming the centres would not be ready until 2011.
Matt Wrack, FBU General Secretary said: "The project is in meltdown. The only real option is keeping and upgrading our existing fire controls and getting the new digital radio system in place.
"This is a scandalous waste of public money and more delays will make it worse. This is at a time when fire brigades are looking at major cuts because of a lack of cash.
"To continue with these plans in this state is entirely irresponsible."