Discovery refusing to cancel or move my debit order

I went over from my works medical to paying my own contribution as I got a new job. My old employer was billed in arrears and therefore I also still get billed for in arrears. When I switched over to paying my own contributions I selected the 1st as my debit order date, but only get paid on the 3rd of every month. I contacted discovery to change my debit order and they said the next debit order is only the 10th so I said ok change it to the 10th. Only to be told sorry but you will have to pay a double contribution which is almost R14300 in order for us to move the debit order date. Which I cannot pay all at once so I asked them can I cancel my debit order and then just do an eft every month as it will only be 2 days later than the debit order payment. And they refuse to cancel my debit order. Their response is, I can make an eft 5 days before the debit order is due to come off. But obviously they don't understand i only get paid on the 3rd. They will not compromise at all. And I keep getting the same response. I get charged banking fees because the debit order keeps bouncing. So tell my discovery what are my options or should I rather go with another medical aid?