extra charges

This rain thing is so bad, I had asked them around june to cancel my rain howver they said they going to deduct 499 first and cancel with i did not have a problem with, than they send me a notification on my rain account advising that they have cancelled the contract, on the 25 july they deducted the 499 okay no problem , i checked and the contarct was not cancelled i sent a mail again asking them to cancel but still nothing, now everyday they are trying to deduct another 499 which i do not understand why and everytime they try to deduct with insufficient cost it is affecting my bank charges now am seating at - 280 for insufficient funds. I paid them jun and july why should they deduct again now ?