This has been confirmed by Royal Mail.

The Trading Standards Office are making people aware of the following SCAM.

A card is posted through your door from a company called PDS (Parcel Delivery Service) suggesting that they were unable to deliver a parcel and that you need to contact them on 0906 6611911 (a premium rate number).

DO NOT call this number as this is a mail scam originating from Belize. If you call the number and you start to hear a recorded message, you will already have been billed £15 for the phone call.

If you do receive a card with these details, then please contact Royal Mail Fraud on 02072386655 or ICSTIS (the premium rate service regulator)