All India Institute Of Medical Science [AIIMS] — online payment

Candidate name - nihal rahman karuvalli pathikkal
Candidate id -[protected]
Sir/mam, i have registered for aiims 2018 and successfully completed step 1. But even after paying for the 2nd step through net banking (An amount of rs 1500/-), it shows that it is not completed.
When i try to pay again it says "a payment has already been made for the same reference number. Your request cannot be processed.". I got stuck here and is not able to complete further steps.
Help me out from this. All seats are getting filled, please resolve this problem as soon as possible or refund my money so i can try to make my payment again...