Unable to allocate EFT payment

YDE is struggling to find the EFT payments that I make. I am paying via EFT using YDE's bank approved beneficiary bank account number. I make the correct monthly instalments and use my YDE account details as bank description. The payments go off of my account and I am sitting with all the proof of payments. For the past three months their accounts department has been calling me telling me that I am overdue. I keep explaining to them that I make the payments via EFT. They tell me to send the proof of payments to their accounts fax/email, but nobody is receiving the documents that I keep sending at my expense. At one point they handed me over to debt collectors, to whom I sent proof of payments and all was sorted, for a month. Apparently they need debt collectors to handle their accounts because they are unable to do it themselves. I have requested that the person from the call centre that phones me to give me his/her email or fax number so that I send it directly, without any success. Have requested to speak to manager on several occasions, but the manager is always either busy or will call back later, which never happens. I am closing my YDE account soon, too much of a hassle.