Carillion, formerly called Tarmac Servicemaster, claims that it was underpaid under the terms of the original contract because of this error. It wants its fees increased by £202,088 a year, backdated to April last year, when the contract started. The company blames the floor dispute on a "material error or inaccuracy" in data from the trust.
Carillion also wishes to recover £632,324 in charges that the trust has refused to pay and is seeking a declaration that documents signed by it and the trust should be binding on both parties.
The trust declined to comment.