I had a thought yesterday when receiving a call from one of my old customers.

I am not fully freelance anymore. I now work a desk job and do the IT work on the side. However it did cross my mind that many companies out there don't adhere to AV/security policies and are always at risk. Because of this risk that means that it's only a matter of time before they reach out to me for aid. I believe that since it's an emergency and that they aren't just a small "mom-n-pop" establishment that the situation is highly critical, work stopping, and causing loss of resources/revenue that I should charge a premium if I'm the only option they have and I have to alter my schedule to assist them.

What I want to know is, how much is too much to ask for compensation?
Personally in that specific situation I would like to employ this:

$189.00 an hour, first half of the day paid in advance for each day.

I also am considering a very generous guarantee of work for 1 week. Since it's a virus you can't guarantee anything but I figure a week allows proof that I cleaned it properly and taught them safe practices as well.