Incompetent accounts department

I switched from EFT to debit order last year, they never acknowledge or put it through on requested date. When I queried, Joshua called and apologised and said that it would be put through, but that we owe a certain amount for license fees (which I paid that day). When I asked him if we'll be in arrears, he said no. Then called back saying that they made a mistake and we will be in arrears but because it's their mistake they would take it off in 2 payments, first payment was done but not second one. Then a few months later I got a statement saying that licence fee is different from one Joshua gave me and that second arrear payment wasn't taken off. I called, spoke to lady called Taylor which said no one available but they will get back to me. Then got an invoice with normal amount to pay, but debit order went off for much more. When I called Joshua again, he couldn't remember what I was talking about but said he'll look into it and come back to me. After numerous emails to different people, including Joshua, at SOS no reply. Then last month an amount was taken off via debit order, my husband called and spoke to Joshua, who said that now (in March) the last payment will go off for which we were in arrears (because of their incompetence), but it will be a lot less than last month. Then same amount went off, although we got an invoice that is much less than debited amount. I've been trying to speak to someone at their offices, but everyone is conveniently unavailable to try and sort the problem they have caused, out.