Originally Posted by
JayKay
'19 - ALTERATIONS
The Employer reserves the right to alter these terms and conditions of employment where this is deemed necessary for the success of the business. Any variation to these terms and conditions of employment will be notified to the Employee within one month of the date of such alteration'
Direct quote from my contract.
Well that says to me they would have had to tell you before changing your notice period.
Most contracts have something similar. But its usually along the lines of a notice period may be extended if a position is deemed critical to the function of the business and they need time to find a replacement.