Hello Criag,
I would not expect the call to come out of the blue, and if it does, you have every right to say that it is not a convenient time to speak to them and arrange a specific appointment.
ESA is actually an indefinite award, so it is possible that even without covid your review might not have happened after 3 years. With the delays that covid has caused it is even harder to predict.
But to your question - let me repeat, if they ring you up out of the blue, explain that it is not a good time to take the call, and arrange an appointment with them.
Catherine
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
