If you had an agreement that the companny would pick up the relocation costs, even if they exceeded the relocation allowance, then you can enforce that agreement. To the extent (if any) that you may have acted in bad faith (since all agreements impose an obligation on both parties to act in good faith) and incurred excessive expenses--more than was reasonable necessary or expected--it is possible that the employer may have a defense to those excessive expenses. But otherwise--and especially if the expenses were not excessive; just what it reasonable costs--if there was an agreement, it is enforceable. The issue, of course, is proving the existence and terms of that agreement, if it was made orally or verbally--witnesses help, though there are limits to the ability of a witness to testify to what they heard another person say (the hearsay rule) that makes witness to an oral agreement not quite as useful as one might hope.Note that if the company is going to treat you in a way you consider unfair, violative of agreements between you, etc. over relocation, they may do it again in the future (especially if you get into an adversarial position with your own employer--and taking legal action, for example, will certainly put  you into an adversarial relationship with them); you may wish to consider other employment options when you have the chance.