Ofwat's decision to reject Thames Waters' bid to increase prices by 8% is final, but Thames Water could appeal to the Competition Commission.
The company said: "We will review the decision carefully before deciding on our next steps."
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Former prime minister Gordon Brown has paid tribute to Kofi Annan, who has died aged 80.
Both men were fatally injured in the smash, which happened at around midday.
A state funeral has been held for many of the dead in Genoa.