How long does probation last ?

[Mephisto123]

I am working for a company and have been with since January. I have resigned (11 Nov ) and plan on leaving on the 2nd Jan. My contract states that I would be on an initial 12 week probation, which could be extended at the company's discretion and I would be informed in writing that the probation is over, I never received any notice. They are saying I have to work my 3 months notice as stated in my contract whilst I believe that since I never got notice of the end of probation, then I don't have to work the 3 months. I have given them 7 weeks notice.

[atticus]

Are you able to post the exact wording of the relevant clauses?