Customer service please

I’m trying to contact customer service as my order from November 2022 never arrived!The order was placed and dispatched via DPDAn attempted delivery was made but no card left so I was unaware of the attempted delivery and that my parcel was left at the local collection point until it was too late and sent back.I was advised a refund would happen once the parcel returned to depot but as of the 6th January no refund has been received back to my account.Can you please advise