GSTR 3B - FILED B2B INVOICE UNDER B2C LARGE INVOICE

I HAVE FILED B3B INVOICE WRONGLY UNDER B2C LARGE INVOCE CATEGERY ON 2017 SEPTEMBER, AND PAID TAX ALSO.

FOR THIS INVOICE MY CLIENT COULDN'T ABLE TO  GET ITC  SINCE THIS INVOICE IS NOT REFLECTED IN THIER ACCOUNT. SO THRY ARE ASKING ME TO PAY THE TAX AMOUNT BACK.OR THEY MAY DEDUCT THE AMOUNT IN MY FUTURE BILLS.

HOW TO SOLVE THIS ISSUE SOR. ONCE GOVT OPEN SEPTEMBER 2018 AMENDMENT FOR B2C INVOICED, I COULDN'T ABLE TO DO IT.

WHETHER SHALL A ASK FOR REFUND AND FILE A NEW INVOICE OR PL GIVE  ADVICE SIR, TWO YEARS IT IS DISTUBING ME.