Unhappy with the debit order

I took up an insurance with discovery for my car and building structure , I told the call centre agent to please start debit my account 22nd of every month for my cover, then they decided that they wont do debit order for the 22nd of every month they will debit first day of every month and I am not happy about this , as when I checked my bank statement I see they debited my account twice first was R400 and something rands and then the agreed amount, first I don't know what or were they think I get the extra money from, and when I called they told me that no they had to charge for Pro-Rata and the fault was with the agent and there is nothing they can do and they wont refund me the extra R400 they took from my account and i asked the lady from call centre to amend the billing date again as the debit order has not went through she then say yes she will do it but they will charge me extra again for the Pro-Rata, another issue is i am told that they cannot find my insurance history as i did specify that i have had insurance for more than 5 years. I am fed-up already with this insurance, i was happy with my previous one.