Indigo Airlines — Indigo Airlines refusing to edit the mistake in surname

Address: Kolkata, West Bengal, 700094

Hi,

I have a booking with dated 15.02.2017 from Kolkata to Hyderabad and 19.02.2017 from Hyderabad to Kolkata along with 4 other travelers. For one of the traveler, the name provide in boarding pass is Pratik RoyChoudhury. The name on ID proofs has Pratik Kumar written as he does not use the last name on the government ID proofs.
I called Indigo airlines to rectify the surname info on the boarding pass as the travel agent did some mistake but they are refusing to edit the surname.Please help.

I can provide all my valid ID proofs.

Passenger Name mentioned on boarding pass - Pratik RoyChowdhury

Full name - Pratik Kumar RoyChowdhury

Name mentioned on ID proofs - Pratik Kumar

PNR -LGSU2E

Thanks
Pratik