Town have called on the Premier League to slap a transfer embargo on Swansea City for their failure to pay cash due from Tamás Priskin's loan at the end of the season.
The Swans are understood to be refusing to pay wages and the £160,000 bonus owed to the Blues relating to their promotion via the play-offs, made up of £20,000 for making the top six, £40,000 for winning their semi-final and £100,000 for victory in the final.
Chief executive Simon Clegg said: "I am hugely disappointed that a legally binding agreement reached in good faith by both clubs as part of Swansea's final push for promotion is now being disputed.
"I am genuinely delighted for Swansea City and their fans but the attempted re-negotiation and deliberate misinterpretation of agreed terms by their chairman is not fitting for a club which has just secured the ultimate prize in Championship football and with it a £90 million windfall.
"Tamás arrived in Swansea fit and became injured whilst under their care. That's football, but contracts have to be honoured and I have absolutely no interest in re-negotiating the agreement.
"As a result of Swansea refusing to pay our invoices, I have reported them to the Premier League, sought an immediate transfer embargo and am now seeking full payment of all outstanding sums with the agreed contractual interest rate of 5% above base."
Priskin joined the Swans at the end of March but made only four substitute appearances, scoring one goal, before picking up a knee injury.