Dear Have you got written test call letter? If they have asked in it to bring the challan then you'll surely need it, but if they have not written they its not necessary at the time of test. Tell them straight away that you have submitted fees n mentioned challan number in the application form hence they should verify from the list they have received from NBP/SBP.

Do not worry and concentrate on the test preparation, meanwhile try to find out original one they may ask you at the time of interview otherwise they'll ask you to submit new one alongwith appeal fee of 250 Rs. No any other thing to be worried.

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Your attitude, not your aptitude, will determine your altitude...Zig Ziglar