Replacing Rear Wiper Blade for 2011 Toyota Sienna

I took my 2011 Toyota Sienna to Ourisman Fairfax Toyota to get an oil change. We’re clocking in 160,000 miles. The service staff who checked me in asked if I needed anything else besides an oil change. I figure I should get a new rear wiper blade. Obviously I had to pay for the part, but he also charged me for the installation. I told him to cancel the service. I just wanted to pay for the part ($18).

The trick to replace the rear wiper was to turn it on. When the blade wiped half way through, turned of the engine. From there, I just popped off the old wiper and replaced the new one. A YouTube video shows how to that in 1 minute and 7 seconds. Ourisman Fairfax Toyota was going to charge me for this, how greedy?