How exchanges like Yobit manipulates the market

Is this pure greed or manipulation to keep the funds on their exchange?

On Saturday 6th of January 2018 I wanted to withdraw Doge from Yobit the withdraw fee was 2 doge but I kept getting an error that the withdraw can not be prossesed. I left it and thought I would try again to day 8th of January 2018.

I was shocked the withdraw fee was up from 2 doge to 100 doge.

A opened a ticket querying the high fee and what happened a few hour later the withdraw fee went up again to 300 doge.

So I am asking is this greed or is it market manipulation?