Account deductions

Our agreement with Dial Direct is that they should deduct my premiums on the 30th of every month, i am always having issues with this people of ducting on 5 or 6 days after the agreed date. like today the 15 January 2015 they just went to my account and deduct money, our agreement is not the 15th of every month but 30 of every month. If they want me to leave their insurance company they must let me know because they are not consistent. They must reverse back my money because that's the money i was supposed to use for January, i am tired of always running to the bank to get money being reversed because of Dialdirect account department's inconsistency. They costing me with penalties at the bank because sometimes they deduct last my last money..