Mango Airlines borderline *******

I booked a flight and tried to cancel 7 hours later after finding out that I do not have enough funds in my account. Tried tirelessly to contact Mango but been shut down with their "No Refunds" policy. Even after me explaining that I have debits of more serious nature, all they care about is the R2500 they going to score out of me. I have been requesting their bank details so I could have my bank reverse the transaction, even that cannot be given to me. According to MY knowledge, section 17 of the Consumer Protection Act applies, provided that I have given reasonable notice to cancel. I think 7 hours notice is reasonable enough as the flight is only booked for next year.