Unless she is 5 year old no court will take custody petition other than visitation; same time they will order her maintenance too, force you to pay to mother as child expenses;
In India Father fighting for Child custody is waste of money, that also for girl Child; unless your ex wife is married second time, your case may be considered for visitation.
Court may order huge sum or deposit and nominee as mother. for me Court ordered 10 Lakhs for one visit.
if you call her again tell her, she is not harassing you, but she is torturing innocent child keeping away from you.
when child is grownup she will know and show the mother what she has done.
thats it. AND ignore their farther tactices or calls.
Best thing you can do is
keep deposit in child name with you as nominee.
if child is your blood, someday she will come to you. and live with that hope.
BEST OF LUCK.