unhappy

I fell 1month behind with my installment of which i contact vodacom and a arrangement was made that the following month about R450 odd rands will be deducted from account but 2days later when there was no funds they ran the debit order of which i have to pay the R100 charges again, i called again and and asked the agent if we can split the arrears into two months and he said they cant as if he puts in the debit order it will go for the full R737 of which i cant afford so we agreed that instead of the debit order going off Im going to pay R450 cash and than call back for the debit to go off I got a reminder sms on the 25th notifying of the arrangement and I paid the R450 on the 25/10/2019 but on the 26th a debit of R737 went of which insufficient funds was avail and for that I'm being changed R100 which was not part of the arrangement