You can write a letter or send an email. I think that a letter will be more effective. They have suggested some arguments to make about how important it is for the Peers to safe guard the NHS but I think if will be more better if I personalise it. I will let you know how I get on.
(many thanks for top UNISON NEC member Mary Locke, who was busy "reminding" us to sign up at the NEC meeting on Wednesday)