Why worry about the legality of the document? Why put time and effort into arguing about it. It looks like it will expire soon enough anyway. Find a new manager and engage them to take over from the apparent end date in 2018 of the current agreement with the current manager.
Agreements often have clauses favouring the manager requiring considerable notice if they are not to be reengaged. Rather than arguing about whether that does or does not apply to the end of a contract period, just give them notice now.