Samsung makes the best monitors, you'll be hard pressed to find anything better than a SyncMaster in your price range. If there are existing problems with your display I recommend calling their support line and if necessary getting a replacement or repair under warranty.
If you're willing to spend a bit more, Samsung has some very nice 27 inch LED monitors which are typically around $350 CAD (should be around 200-249 pounds)
I highly recommend spending the extra cash because the flatpanel market is very mature right now. Nothing is going to be changing in the near future and as such, monitors are probably the most future proof investment you can make at the moment.