They don't care about their customers

I don't understand Clientele, always when they have to help me they say they will help me but... and this is due to the installment I missed in December which it is their fault as they debited me on the wrong date that we did not agreed on, we agree to debit on the 25th of every month but in December they debited on the 15th without my consent. And now with all my case I log with them they always say that just because I have skipped the December installment and results is I don't get full benefits. This guys are just not willing to help me further, I appreciate their effort but why can't they offer that they double debit or refer me what to do to get full benefits again? This guys don't go extra miles to help clients, they only care about my installment.