GSTR 1 REVISION

During the Jan to March quarter I issued three bills and had opted for Quarterly GSTR 1 filling. While filling the return in April I entered the GSTN of receiver incorrectly. The incorrect GSTN was also of the same firm(which was discontinued)so I came to knw about the mistake and then rectified it in the GSTR 1 of May month. but the receiver firm is saying they haven't got the credit.