Debiting account after cancellation

i app**** for a rain sim card in March, my first payment was on the 27th of March. i received and activated my sim card on the 1st of April, which means i was paying in advance. i have cancelled my sim card in July and received confirmation that it will be cancelled from 1 August. On 1 August my account was debited. How do i get my money back from you seeing that no one responds to email or support cases that i logged. i only had the simcard active for 5 months yet 6 payments was taken