Way down the list of options is posting a new contract with the requirement for the recipient to sign within 90 days or walk away. Before you say that it can't be done, this and former threads have concluded that it can and furthermore under current legislation, if one does not sign, one will be deemed not to have made best efforts to reduce their losses and the subsequent dismissal settlement will be minimal.
A little story
When BA took over my airline, the Engineering section agreed not to sign the new contracts and everybody handed in their new contracts for the unions to hold. Over the following weeks one-by-one people went back to the union reps and asked for their contract back so that could sign it and send it to BA. On the last day for signing there were about 8 of us left in my union that hadn't signed the new contract. With a young family it was at that point I capitulated. In the end there were about 3 people who held out who were subsequently 'let go'.
Yes they won their court case, but they weren't on such good money as they had been.
This story could be repeated very soon