Some weeks ago upper management gave me the task of updating the company's website without telling it to my team leader. They were clear that this task was going to be unpaid and should not interfere with my current assignments, also they gave me a soft-deadline of 1 month to do it. They also said that it wasn't a mandatory task, and my decision would be taken into account. While I knew that it was going to be a lot of work, I decided to do it just to refresh my front-end skills and to disconnect a little from my painfully boring back-end job.
What happened? Well, I got really engaged in this task and it interfered with my current assignments to the point that my team leader noticed my drop in performance and connected the dots after catching me working on the company's website. Then he reported me to upper management and I had a meeting with the person of upper management who gave me the task. In the meeting they said that the website was an optional task and that I owe the company 3 working days (24 hours). On top of that they asked me to go back to my back-end duties and give them all my progress related to the company's website. After this I felt quite frustrated as I was starting to enjoy creating the website, and I believe it was an unfair request considering that they know that I regularly do unpaid overtime (around 20 hours per month).
Now I'm starting to look for another job, but I am not sure if I should work these 3 extra days, or tell upper management to take them from my vacations or simply not pay me for them. Which is the wisest decision?
Extra information:
I am part of a team of back-end workers, and our company is a consultancy company.
This is the US but I am not an at will employee.
I am leaving not only because of this incident, but because I don't enjoy my work, the working environment is quite toxic to the point that sometimes I have nightmares about it, and I am paid below average.
Thanks for reading.