GST query need help

NITIN SABOO (344 Points)

18 November 2018  
One of my friend's accountant, issued one bill number 156 in favour of two parties name- A & B and both parties shown in their GST return.

Accountant corrected bill number in his records by issuing bill number 156 to A and bill number 193 to B, but not informed to parties, both bill values are different.

So, please suggest how can we rectify the mistake.