ITU assist is taking you money and dont pay for services to help your clients

Good day, I need someone to contact me very urgently. ITU Assist send us out for a geyser replacement. We could not get stock as they were over due with there account at Plumblink. Arrangements was made to get the stock on your account. Now 3 months later still no payment and ITU Assist said we must get payment form your client as he is only covered for the geyser, valvepack and tray that we received from Plumblink. Your client must pay for the COC, installation cost and pipes and fittings. I know that is not true so please contact mu urgently.