Kirstie’s mother was furious when her 12-year-old daughter came home from a school trip to Austria with her biggest ever mobile bill.

Jo Peacock, an IT manager from Welwyn Garden City, Hertfordshire, confiscated the phone and rang Vodafone to find out why the bill was so high.

She discovered it was not Kirstie who was to blame, but Crazy Frog.

Mrs Peacock had let her daughter order Crazy Frog’s Axel F ringtone on the Jamster website, without realising she would then receive reverse-charge texts until further notice.

Ms Peacock told the BBC News website: “I was disgusted to find each text had cost �3. While Kirstie was in Austria I had been charged double as she had been roaming. To say I was livid was the understatement of the year.

Icstis, the premium rate watchdog, is due to report on Crazy Frog in August after similar complaints. It is also looking into claims the Crazy Frog ringtones, an over-16s service, were aimed at children.

Premium rate services for under-16s must not cost more than �3.

Axel F by Crazy Frog topped the UK singles chart in May, but the cartoon character’s reworking of the Beverly Hills Cop theme tune was an even bigger hit as a ringtone.