Unhappy customer

To be honest I haven't had an issue until now. I paid my loan via EFT on 22 December. 31 December they deducted again. In between the 22nd and 31st,I sent emails and tried calling but wasn't able to get through to anyone and I just put it down to them being on holiday. I have app**** for another loan and it just says pending and I don't need the money anymore so want to cancel it,scared they'll debit again even though the money was not dispersed.