Is company allowed to just double our notice period?

Can someone help me… it is clearly stated that according to the law you can change your job, with a prior notice to your current company of 30 days. My question is, last month my company was accepting the 30 days but they woke up one day and made it 60 days. When I signed the offer letter nothing of the kind was on the paper, please let us know who will cater for our needs for the 60 days and why there is an additional 30 days after you resign? Secondly why waste my 60 days while my contract has ended and I never meant to renew? Arkan fraternity, UAE