You do not say where you live or whether you have taken a hackney carriage or private hire car. If you are in London, you may have used a minicab which are not currently regulated so they can do what they like. If you are outside London, there are two types of vehicle. A hackney carriage can ply for hire in the street and you can hire them at ranks and flagdowns. They are required to have meters set to a maximum scale if the local council sets one down. They can reduce the charge if they want but can't charge more than the maxiimum. There are also private hire vehicles which work by prior booking so, if you phone for a car, this is probably what you got. They are not required to have meters and cannot be limited in what they charge by the council. The charge is by agreement with the customer so it is expected that you agree a fare before you undertake the journey. If you don't, they can charge you what they like. It could be that they sent you an unlicensed vehicle. If this is the case, or you are unhappy with the service you get, take the vehicle number and speak to the Licensing Section of your council.