Setting a price alert on londonstockexchange.com

[forgotusername]

I use the LSE email alerts facility to get heads up on important RNS's, mainly because Investegate can't seem to make their system work. I recently discovered that you can set an alert if the bid or offer price crosses a given value. I have a stock I want to sell if the bid price goes above £n and set the alert accordingly. The next day, I got an email at 07:45 saying the alert had triggered but of course when the market opened the bid price was way below my target.

The next day, the same thing happened so I just reset the alert. Today, I again got an email at 07:45 which I reset, then at about 11:00, I got another email. I raced to my computer to check and found no sign of a price anywhere near my target.

It's a potentially useful facility but only if it is accurate. Does anyone understand what is happening here?