On Sunday evening a received a urgent request from a client on advice regarding a website of theirs that was running slow and causing the server to crash.
I provided a lot of advice about the best course of action and ran numerous diagnostics tests on the site.
I invoiced the client for 2 hours of consultation time as it took me a large part of Sunday evening and Monday morning to help them solve their problem.
The client is surprised I have charged for my time and is requesting I don't charge for it as I didn't advise the clock was running when responding to their emails.
Is it fair to charge for this or should I just let it go?