The striker's representative complains that the Dutch side have altered their asking price from an agreed fee in January, with a £12.1 million offer plus bonuses still not enough
The Swans have been locked in negotiations with the club for some time and chairman Huw Jenkins fumed on Friday that they may be forced to withdraw their interest in the player.
Now Francis Kacou has publicly criticised his client's club for increasing an agreed asking price over a six-month period.
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"Swansea wanted to pay and Bony has seen that but Vitesse wanted more. Now there is an offer of €14m (£12.1m) plus €2m (£1.7m) in bonuses.
"Why is Bony still in Arnhem? We do not know what they want."
The Ivory Coast international was in lethal form last season, at one point embarking on a run of 15 goals in 10 consecutive Eredivisie matches.
"One thing is for sure, he will not be playing for Vitesse this season," Kacou continued.
"West Ham, Everton and Liverpool have been reported as having an interest but Swansea has made the best offer. I want clarity and a promise is a promise."