A ressurgence of an age-old domain name sales scam has started again, with scammers UKDNR (calling themselves “Domain Name Registrar”) are telephoning .uk and .com registrants, with a high-pressure sales tactic based on the false claim that someone is attempting to register domain names similar to yours, then offering to register them ahead of this fictitious 3rd party at a vastly inflated price.
Anyone receiving unsolicited sales calls regarding domain names and hosting should regard such calls as fraudulent, and under no circumstances should you give these scum your credit-card details.
If you want to buy additional domain names, always use a reputable domain registrar, accredited for the domain TLD you’re interested in, like Othello Technology Systems Ltd at www.OthelloNames.net an ICANN Accredited Domain Registrar
See Domain name sales scam for the official Nominet statement.