回复：回复：you can do it yourself.

If you have not done it, do it quick.Use trackable express mail (Fedex or UPS). You will be in status if your I-539 is accepted by CIS before your current F1 expired. Remember to check whether correct amount of filing fee (no more, no less) is included and your signature is there. If the case is rejected (returned), you will be in trouble. After your case is taken by CIS, you will be in H4-pending before a decision is made on your application.