Accountant charged me to respond to IRS Inquiry?

[Robert M.]

I received a CP2000 notice from IRS and send to my accountant who prepared taxes. The inquiry was resolved with a simple letter to IRS explaining where income (rents) were accountant for in LLC return.

The issue was resolved but I just received an invoice from accountant.  

It seems to me that since the accountant prepared the returns that I shouldn't have to pay for the response.  The fees the accountant charges for tax prep are very high.

Should I pay for the response service or not?