Paytm Mobile Solutions — refund not received of rs. 8000

I have ordered a phone lenovo k8 note on paytm mall app order no. [protected] on 27th of december 2018. After an hour of order i cancelled my order. But i didn't received my refund back of rs. 7999 (Order was of rs. 8199 but 200 was paid through paytm wallet and that was refunded in my paytm wallet) but remaining rs. 7999 has not been refunded so far into my sbi bank account as same amount of transaction was made by me through sbi upi id. After contacting paytm customer care, they replied with that " we have refunded your rs. 7999 towards sbi bank, now should contact with sbi bank that how much time they will take to refund the amount into my account. Then after contacting sbi customer care they said ask paytm to provide reference id through which they have refunded your money back to sbi bank. After agian contacting paytm customer care they continuously keep saying that we have refunded your amount to bank, you should contact bank. Paytm is harassing me mentally. I request you please refund my money back to my account as soon as possible. As i'm a student and i'm vey far away from my home. I'm suffering alot, plz for god sake refund my money back.