I think you have to submit fee in the specified branches where PSC have its accounts.

SPECIFIED BRANCHES OF THE NATIONAL BANK OF PAKISTAN.
Main Branches are:-
1. Parachinar, Mardan, Swabi, Malakand, Shangla, Chitral, Timargara, Daggar, D.I.Khan, Bannu, Karak, Kohat, Hangu, Lakki Marwat, Abbottabad, Haripur, and Mansehra.
2. Saddar Road Branch, Tehkal Payan Branch, and G.T Road (Nishtar Abad) Branch Peshawar and University Campus Branch Peshawar.
3. Tehsil Bazar Branch Charsadda, Nowshera Cantt: Branch, Bank Square Branch Mingora and city Branch Tank.



Whichever city is near to you,go to its main branch of NBP and submit the fee.