There are now lots of companies competing to offer telephone and broadband services to consumers.
Competition has many benefits, including choice and ultimately lower prices.
Companies use a variety of sales and marketing activities to gain customers and while the majority of these are carried out responsibly, some companies may attempt to gain customers through dishonest activities such as mis-selling.
There are various forms of mis-selling, one of which is known as “slamming” which is where customers are switched - or attempted to be switched - from one company to another without their express knowledge and/or consent.
In some cases, you might only be aware of this once you’ve received a bill from a different company.