Is it new and under warranty? If it is then call the manufacturer.
If not it may just need a service - but don�t necessarily call the manufacturers - they charge a fortune just to come out and tell you it�s not working!
Ask your neighbours if they can recommend a good local (corgi registered) plumber - one they either know or they�ve used.
Personally I�d seriously avoid the yellow pages these days.
The plumber I use has been around for donkeys years and is always busy. I�d rather wait a couple of weeks for him to come and fix something as I know he�ll do a good job, will charge a reasonable rate and has that rarest of all qualities these days - he takes pride in his work.
Hope this helps and you may find more responses if you duplicate this post this on �How it works� and �Home and garden� and hope that someone like Stanleyman or Buildersmate picks it up, but point out it�s a duplicate.