Rain Deducting money from account without authorisation

i have cancelled my services with rain on the 9th of September and Rain already collected my router ( we had no service for the month we where using Rain so decided to go with a Fiber Company) Rain deducted money from my account on the 1st of October and I an mot receiving any feedback on my inquiry as to why they deducted money from my account and when I will be refunded as their services was paid upfront.