Unprocessed transaction not reserved back to my account

I made an online purchase from ZARA and money was deducted from my account with a pre authorisation status on the 27 December. on the 1st January a duplicate amount was deducted from my account by ZARA, the deduction that was taken on the 27th was not processed when I check my bank statement. I went to the branch and the consultant told me that ZARA needs to pay back the money into my account and if ZARA is unable to assist me they will charge me to reverse the money. till to date the traction has not been processed so I don't understand how ZARA will pay me money that was not processed by the bank.