Birmingham boss Steve Bruce claims he is 'within his rights' if he decides to alter the transfer fee for want-away defender Matthew Upson.
Birmingham have rejected bids of £4million and £6million from West Ham for Upson who has 17 months remaining on his contract.
The player has made it clear he will not sign a new deal and under FIFA regulations could walk away in the summer if he pays up the remaining 12 months of his contract.
But Bruce brushes aside suggestions from the player and his agent Barry Neville that the midlands club keep changing the sum of money they want for the 27-year-old.
Bruce said: 'Matthew Upson is our player. He's got 17 months left on his contract and I can move the goalposts if I want to. The club can as well.
'If anyone has been misled that he's available at a certain price, with the way the market is, then of course I'm within my rights to demand whatever we feel. The club are within their rights as well
'Matty has to accept that. Once you sign a deal like he did, for five and a half years, you put yourself firmly in the club's hands.
'If we demand a certain amount for Matthew Upson, then that's our prerogative.'
Bruce remains adamant he wants Upson to stay at St Andrews even if the Hammers come in with a third offer in the next 24 hours.
He said: 'Given the timescale, how can I replace him? Where can I find a left-sided centre-back with seven or eight England caps who has played at this level for four years?
'The answer is I can't, especially with only a day and a half remaining before the transfer window closes.
'I've said several times now that such a move will have a negative effect on the team and the supporters and I want Matthew Upson to be in our team to lead us to where we want to be - back in the Premiership.'