Bad service - Momentum short term insurance

I am tired of MSTI getting my debit order date wrong. This is the second time, i tell the to change my debit order date, they always tell me they cant change it immediately because of some system(the say some jargon). The first time it happened, it was in June. Yesterday, i spoke to some very impatient agent, she told me the same thing. They cannot change the debit date due to ....she spoke some jargon i dont even understand. When i told her, how am i going to know its done, since its the second time the same thing is happening, she got really irritated, with some attitude. I asked her to not help me with that attitude and asked that someone else call me. She said her manager will call. Its 2 days, no one has called. I am still sitting with unpaid premium and money in the bank.

what is so difficult, for Momentum Short Term Insurance? i get paid on the 26th, i want my premium to go off on the 26th. Why do they get it right on other months and get it wrong on other months?

Do they even understand the impact of unpaid debits, twice, from the same company? This is frustrating. i need help