The original date of March 16 was scrapped last week when the Mexican withdrew citing a stomach illness.
Alex Morrison, Burns's manager, announced yesterday that ties had been severed with the promoter as they felt that the 29-year-old's career was stagnating.
He also revealed doubt that the bout with Vazquez would ever actually happen.
However, Warren has said that he has consulted with his solicitor and will be seeking damages.
"Vazquez is contracted to box Ricky Burns on [April 20]," Warren told The Guardian. "He has confirmed that he will fight on that date. Everybody seems to be cancelling it except me – and I'm the one who's putting up the money.
"All of these people, including Alex Morrison, [talking] about no contracts some time early this evening, certainly no later than Monday, will all be receiving solicitor's letters asking for apologies and damages.
"I have a contract with Vazquez, on my website. You can see the letter from the IBF. And in the meantime I have a contract with Ricky. I like Ricky, I don't want to fall out with him, and I'm not making any other statements about it."
Burns was left frustrated in November when Jose Ocampo withdrew at late notice due to the death of his trainer.