Debit note declared as a buyer

Hi,

I have purchased 20 items of some good X for 100 rupees. Later I returned 10 items to the seller. My accountant declared it as debit note in GSTR - 1. We didn't receive any credit note from the seller. This happened in July 2017. Now, there is a discrepancy in my 1 vs 3B. Because of the debit note in GSTR 1, the Tax liability as per GSTR - 1 is inflated. Tax officials are asking me to pay the difference. What should I do now? can the seller still issue me a credit note for these items I had returned? (I am making use of small numbers for my own understanding)