Hmm, good one, I"ve never had this at any games I"ve run.
If the player says "call" and throws the 1k chip in, then he/she"s forced to call the whole bet, meaning the full 3.5k, no question.
I think you"ve got to ask one question - if the player throws a chip into the pot is he/she automatically assumed to be calling, regardless of any verbal announcement ? Some TDs may, whereas others may not. If the assumption is a "call" then the player is liable for the full 3.5k. If the TD thinks a genuine mistake has been made (how the TD could make that assessment, I"m not sure) then I suppose the player may be allowed to fold but leave the 1k behind.
My own view is that the player should have been forced to pay the full 3.5k - if anything, it would have made the player pay more attention in future to what"s going on around him/her. An expensive lesson maybe, but a valuable one.
Or am I just too harsh...?