Sounds like you can legally debate this, but it would not be productive for your long term future at that company to do so. Smaller, local companies usually do this, probably because they see some need to change policies to try protect the business at that point in time (such as very high staff turnover, etc).

If the changes to notice period and probation period is not excessive, then I personally don't see it as a big deal. If its that bad a change then it will impact their future hiring and probably it will be changed again later. I doubt it is that terrible a change but really depends on how each individual feels about it.