Debits money whenever they want costing me bank penalties!!!!

After asking Miway numerous times to only debit my premium on the 29th of each month, they continue to debit whenever they feel like it. The one month they even tried on the 22nd..... this results in me having to pay R150 penalty everytime.... i complained about this and nothing gets done. These last 3 months of them doing this has resulted in me paying a total of R450.. I feel this is unfair of me to pay this because Miway does not listen to my requests!!!! Fed up with Miway