Short rejection after two years
You seem to mix two different aspects: Your (understandable) disappointment about the response and the long time it took to get the response. 

You cannot really complain about the response itself because it generally seems to be rational and the reason for the rejection is not the long time it took. Right now you can only try to use the helpful aspects in the response to improve your manuscript.

On the other hand, you should complain about the time it took. Two years is indeed inacceptable. If you will get no reply, there is very little you can do, I'm afraid. It is probably best to look for an alternative journal.

My advice for the future: Do not submit to the journal again, but count it as an important experience: next time, you could ask in regular intervals (not too short or long, let's say every three months), and also give the process a maximum timeframe.