Citibank Prepaid Card Complaint

Citibank Prepaid card department,

General purpose card Unauthorized transactions/trans. issues Pennsylvania

I purchased merchandise from - - using the prepaid card on -/-/-. I returned some of the product to the store between then and was working with -, from - who said the return was processed. We shared several emails and she sent me an invoice that shows the return was processed but I have been checking the account and it does n't show it was received. I also sent an email again to - from -, and no response, a week later, I sent an email to the general email box for - and still no response.