Rain debited my account wrongly - no agent has contacted me as promised to date

FOLLOW UP 2:

no agent to date has contacted me regarding my issue as promised on the 3rd of December 2020.

I cancelled my SIM card in the beginning of Nov 2020 and I’ve been debited on the 1st of December again. I have tried contacting Rain customer service with someone named “Kealan A” with no help at all. They don’t want to refund me as they debit my account in “arrears” ? Yet I have to pay for the service immediately when I first joined rain. Please, I want a refund immediately as you can not make me pay twice for one month.