Good day, I would like to complain about the bad service we have received from RCS group with whom we have a home loan

Good day, I would like to complain about the bad service we have received from RCS group with whom we have a home loan. Their customer service is absolutely disgusting not helpful at all. I have been requesting cancellation figures from them from April and to today still gave not received them. I had to request them from the attorneys handling our sell. When I received the figures, I discovered the figures are incorrect. One cannot get through to a manager who take actually assist you as you get told you are in the incorrect department. I am at my wits ends now.