Water Metre seems too pricey!

A question about : Water Metre seems too pricey!

Hi
I am a student living on my own, away from home. I have had a letter through regarding my water bill and water metre etc. Having only lived in my flat for less than half a month. I am confused as to why I would be charged the same as other months, something I already feel may be a little too high (Ј25.50). I have asked the letting agency where my water can be found etc and there reply was to give me a reading and the serial number. The reading is the exact same as what welsh water have deemed to be a random calculation based on previous occupants.

What is it I should do?

Best answers:

• If you are on a meter, you should only be paying for what you use.
  The direct debit will have been set up based on other consumption. But not paying for that consumption.
  It will even itself out over the year. Then they will look at it again and change this amount accordingly