The midfielder was close to signing for Fiorentina, but then chose to sign for the Toffees instead.
Mangala left Nottingham Forest for Lyon in France, a club that Textor also owns.
He was initially on loan at Lyon for part of last season, but then signed permanently for the French club this summer.
Sport Witness quote Bia as saying: “I had set up the operation with Pradè and Goretti and the requests of Lyon had changed, which had opened up to the loan with the right of redemption.
“The president (Textor) then decided to give him to Everton, and everything fell apart when it seemed that the thing was in the right of redemption
“The loan figures with the right were for a total of 25-30 million. He was almost leaving for Florence but then everything fell through.
“Could the negotiations restart in the summer? Given the great appreciation of the player and Fiorentina, I think so, but it depends on Everton and the path they will take. But I repeat, the player had given his yes to the Viola.”