I have asked my accountant for the same on a couple of occasions over the years, and was not charged for the service. The letters were brief and seemed to be a stock-reply stored on file, so maybe 5 minutes work max?
I pay my accountant well for his services, and I would regard the letter as a courtesy. I would certainly not pay €180 for it.
As for the bank - unless your circumstances are exceptional - the letter is a formality, crossing the t's and dotting the i's.
Perhaps ask your accountant for more details as to why it costs so much?