Shady hidden extra costs

I signed up for fibre with MindTheSpeed a couple of years ago. Recently I moved to a new neighborhood and kept them as my ISP. This week when I tried to downgrade my line, I was informed that there would be a cost. This cost is not displayed anywhere on their website or any of the documents when signing up. So be very carefull when dealling with them as there may be some extra costs that suddenly pop up. I have cancelled my service with them as I do not want to deal with hidden cost that I have no way of knowing about when signing up.