18866's Terms and Conditions:
Quote:Charges and Payment
We withhold the right to vary any charges or rates at any time by posting the resulting price changes on our website or otherwise giving you notice. All Charges are subject to any applicable UK tax or duty, including Value Added Tax, at the prevailing rate.
There is a connection fee in respect of any call made using the Call18866 Service which is published on the Call 18866 website at all times. The Call18866 Service is billed in one-second increments and all call Charges are rounded to the nearest penny.
questa has a valid point about whether they could suddenly hike the prices and post the 'announcement' on their website. Because realistically, how many of us check their website every day? If they hiked the price then nobody would have a case against them because of the T&C's.