Deducting customers money

DMC made arrangements with me to pay my credit over 2 months. I paid them and after I requested for settlement letter and agent request it for Me.

One the 25th of November they deduct my money again and I contacted them via WhatsApp and the agent said they can assist Me after 24 hours to return my money.

One the 26th I contact them and now they are saying there is nothing to refund me while I settled my account.

Please help me to get my money back