Posting a credit to a different account

SUGGESTED

Good afternoon.  We have a customer (A) who has recently been bought out.  The new owners (B) also have an account.  A has a credit on their account of £332.83  so B has applied that to their balance of £490.10  and just paid the remaining £157.27.  

Is there a way of transferring the credit to B and setting A to zero.

Thank you