Charity Logistics' complaint to the ACU about the ICT Consortium was "ill-judged in its timing, intemperate in its tone and unfair in its allegations", said Carrington.
He said Charity Logistics had refused an invitation to become a delivery partner because it did not trust the consortium to "act in the best interests of the sector".
Its criticisms of the consortium's appointment process would have been credible, he said, had it allowed the consortium to consider its questions before complaining.
"The tone of the allegations... indicated the difficulties the ACU and the ICT Consortium faced in deciding how to respond. The allegations... are not only unwarranted, but they misrepresent the professional standards to which the members of the consortium were trying to work," he said.