Where the plaintiff seeks the recovery of money, the plaint shall state the precise amount claimed. But where the plaintiff sues for-
(a) Mesne profits, or
(b) for an amount which will be found due to him on taking unsettled accounts between him and the defendant, or
(c) for movables in the possession of the defendant, or
(d) for debts of which the value he cannot, after the exercise of reasonable diligence, estimate, the plaint shall state approximately the amount or value sued for."
If the defendant has not filed the written statement within the stipulated time period then he may not be allowed to file written statement.
However the defendant can file additional written statement if the plaintiff resorts to amend the plaint for any valid reason.
No doubt the defendant can object to the plaint for this reason during final arguments.