Exactly, I think there is more to this as the OP has already started looking for another job without even knowing the on call shift rota could be one weekend in seven if there are seven engineers hardly something to go to the lawyers about.
I sometimes wonder where employees think the money comes from that lands in their bank account every month. In this instance the said company may have landed a new contract to keep their heads above water and thus making sure everyone keeps their jobs, yet you often find you get nothing back...