Well, in my opinion, he is the one who is the source of all
unhappiness, both for him and also for dear. If he had prepared the
payment beforehand and give it to you the moment you complete the
website, you wouldn't need to keep chasing after him, don't need to
give him the ultimatum, and he wouldn't feel being bugged. If didnt
chase after him, I think there is a possibility that dear won't be
able to get the payment le, or it would be super delayed. He cant
really blame you if you are chasing him for the payment since you
have already completed the project a few weeks ago and the payment
is still not made. And if the accounts clerk forgot, that is the
responsibility of the company, not dear's fault as well.
So all in all, it is their fault. It gives a very bad image to that
company as well.