I agree with Flintstone. Your licence is a legal document pertaining to, and belonging to you. As far as I am concerned no unauthorised person is allowed to sieze or hold your licence. Only the appropriate authorities such as the CAA or the police of the country of issue are able to do that. I don't believe the FTO has the authority to withhold it while a contractual dispute is underway. It does not belong to them and they have no jurisdiction over it. (BTW, totally uneducated legal opinion though it is, it's what I have been led to believe here in South Africa.)