Just separately on the second points, contracts can be changed by the employer, what they cannot do is change your contract to put you in a detrimentally worse position without your agreement. Invariably, COE's will state about annual wage rises being looked at but not guaranteed etc. What you cannot do is lower an employees wage without the agreement of the employee. This would be a fundamental breach. However, you can change to make the terms better, for example, giving an extra days holiday, without the employee consent. The employee could still object to this change but is unlikely to, and if they did they would still need to show how the change has fundamentally been detrimental to them.