The distributor and e-commerce group filed a writ against RBS Commercial Services - which formerly traded as Lombard NatWest Factors Limited - seeking to resolve issues surrounding the termination of a contract between the two groups.
The writ, filed at the Royal Courts of Justice in March, claims the particulars of the termination have caused C3000 to be out of pocket for a debt owed to the company by a customer.
"Lombard notified Computer 3000 that it would refuse to credit to [its] account an amount in respect of a debt owed by MSM Macro System Management in the sum of approximately 304,424 euro (£189,417)," the writ states.
The writ also reveals that C3000 negotiated alternative financing deals with IBM Financial Services and Coface LBF.
C3000 managing director Parthiv Desai said RBS had been granted a court extension to prepare defence for the case which, as yet, has no court date. He confirmed it was "definitely going ahead".
A spokeswoman for the Royal Bank of Scotland said it was against company policy to comment on legal cases.