Poor client service, SAGE

I have a small business which uses SAGE. The program is fantastic, but their accounts department is in shambles. I have overpaid twice since the incorrect info was supp**** to me on their invoices. They have paid back the one amount, but now refuses to pay back R288 which is clearly reflected on THEIR own statement as being a credit amount. They have such a leadership vacuum, that nobody from management phones me despite requests to resolve this matter. They would also rather receive free adverti*****t on Hellopeter, than to resolve this matter amicably. Poor client service!