Now you can submit your complain at prague council website. But please do not excpet much more then apology.

Phone a taxi in advance
When using radio-taxi or cabs contacted by phone you get the opportunity of finding out the valid price per kilometre and the company name as well as the identification number of taxi provided by the company. This option is almost safe (although there has been a few incidents reported as well).

Never hail a taxi from the tourist areas and spots
The drivers standing at ranks in the most frequent tourist areas such as Wenceslas Square, Lesser Town or Charles Bridge tend to be extremely expensive and it's not recommended to use them. There are also many rumours that some taxi ranks are controlled by Russian mafia. Even Czechs are very careful taking taxi from such a taxi ranks or hailing a random taxi ...

Use only an authorized cab
It happens than you need to take a cab and there is no phone around. In case like this make sure that you are getting into an authorized, properly marked taxi. It means that it is clearly marked with the identification number, the company name and fares printed clearly on the doors and a black and white checked stripes along the side. If these are missing the driver infringe the regulations and it's recommend to use another taxi.

Verify the price charged by the driver before getting in
The fare must be visible on the front doors. A complete price list including the basic (boarding) rate, the rate per kilometre that should never be more than 28 CZK (at night 40 CZK) and the rate for waiting per minute, must be set on the taximeter as well.

Insist on turning the meter on or even better negotiate price before getting in Unfortunately insisting on turning meter on might not be best option as many scrupulous drivers using some kind of devices which speed ups meter.

Ask for a receipt
You should always request a receipt (ucet prosim), although the driver is supposed to do so without asking. The full receipt must contain: document number taxi company's name and address car's registration number (SPZ) identification number date of ride times and places of departure and arrivals basic rate + rate per kilometre + total distance price including VAT driver's name and signature On the receipt printer out by the taximeter only the starting point, destination and the driver's signature can be filled in by hand. If the driver does not give the receipt or if it is incorrect, you are theoretically not required to pay the fare.

If not satisfied submit a formal complaint ( in reality very little help ...)
If you feel being ripped off by the taxi driver, it's better and safer to submit an official complain than to get into a personal conflict with the driver. Make sure that your complain contains the license number, identification number and company name.