Debit order dispute

Good day I have had multiple policies with old mutual for several years and I am very disappointed with how the service standards have dropped. I have many issues but the urgent one is debit order not being debited on the agreed date or not at all rather and then I receive a message saying I missed premiums, what frustrates me is that I made call to call center to arrange for the debit order to go off and then I get debited twice. Please assist this is unacceptable