The cost of making mobile phone calls has gone up 60% compared with a year ago, according to consumer tv show Kassa.

The rise stems from the way many mobile phone firms have switched from charging customers per second to per minute.
For example, Vodafone will introduce pay per minute for all new customers and those renewing their contracts from Monday, Kassa said. KPN and Telfort have already taken similar steps.
Many mobile phone calls are short, meaning users get through their allowance of minutes more quickly.
T-Mobile and Ben still charge customers per second, the tv show claims.
OECD
In a statement, Vodafone said its research showed 60% of customers would not face higher bills.
KPN argues that according to OECD calculations, Dutch mobile phone fees are among the lowest in the world.
The EU has banned pay per minute for mobile phone calls between member states.