Or is this a scheme to obtain a refund / avoid payment.
In the Parent / Child / Adult relationship, is he not playing the part of a Child
A child has little responsibility and will, for example, say he has done wrong, but then hopes to avoid full responsibility by laying some of the blame on others. ( someone made me do it).
The Child personality can only succeed in this stategy if the Adult adopts the Parent personality and takes on the responsibility that is rightly the Childs. ( This is where you feel sorry for him and offer to solve the problem for him).
The Adult response is to insist the other party remove their cloak of Childishness and accept the consequences of their actions. You say "you owe me the money" or "you will not get a refund".