How can I stop a constant nuisance text on my mobile phone?

it's from a "Carter Forbes" threatening to take necessary action against me if I don't pay my debt to him or them. Of course, I have no debt and have never seen the name before. I hardly use my mobile, few people even know my number and it's fairly new.

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).