Anjum Khan was expected to fill one of three additional places on the board, which were created at the company EGM in February. Although the board considered three candidates, only Peter Sykes and Jim Amabile were co-opted.
The NMA said Anjum been robbed of his place on the board. In a letter to the association's members, committee chairman Mark Proudfoot said: "The action of certain board members is an absolute disgrace. Unfortunately, it shows the Nisa board, despite recent statements, is still working in its old autocratic way."
In a statement released after the meeting on May 2, Nisa-Today's fuelled NMA anger by saying it did not recognise NMA's role or activities.
The statement, which chief executive Neil Turton says reflects the board's view despite the inclusion of two NMA candidates, said: "Over the past year our company has had to deal with numerous issues that this organisation has raised. This has caused considerable damage to our standing in the trade, distracted our executives from being totally focused and resulted in substantial legal costs. We cannot allow these negative politics to continue."
Turton remained confident Nisa-Today's relationship with its members would continue to build and told Convenience Store that plans to introduce a democratically elected council for retailers would be up and running by the autumn.
He added: "This is something we promised members we would be doing. The retail board will be replaced by a retail council with seven elected regions across the UK. Each region will have two representatives apart from the South East and the Midlands which will have three places because they have more members there. It means we will have democracy right down to a grass roots level and that the board can be properly representative."