The latest instalment was that Carillion has been forced into an embarassing clarification of savings numbers previously released following an article in the Sunday Times.
On Monday, it said in a statement it wishes to clarify that "its previous statement that 'as a direct result of the merger, the cost-base of the combined group could be reduced by at least £175 million per annum by the end of 2016' has not been 'audited' in the technical sense."
It added: "As set out in Carillion's announcement made on 14 August 2014, an independent accounting firm has provided public assurance, having tested the basis of preparation of the statement in line with the requirements of the Code."
It is now expected Carillion will make a last-gasp attempt to sweeten its merger offer after having been rejected so far.
It has until Thursday to make another offer, or must wait six months to approach again, as per UK takeover rules.
The pair revealed in June they were first in talks over the creation of a potential £3bn mega construction firm.
It issued a comprehensive statement detailing why it believes the merger is not in the interests of its shareholders and was an "opportunistic" move. Carillion has said a union could reduce the group's cost base by at least £175mln a year.
Carillion shares added 1.14% on Monday, while Balfour rose 2.54%.