Lonergan has been linked with a move away all summer but manager Darren Ferguson is adamant the club will keep hold of their prize asset.
Ferguson, who saw his side beat Blackburn 3-0 at Deepdale on Tuesday tonight, told the club's official website: "They have been in three times now and we have turned down every bid.
"I think everyone has some sort of perception the club is skint but the chairman and the owner are trying to help me as much as they can and to turn down a third bid suggests that.
"We got the latest bid today but I value him at £20million - I don't want to sell him! I'm not being funny but West Brom are not going to get him for what they are bidding, no chance."