Had this response from Tesco to my final email:
I would like to assure you that I have recorded your views and will pass them on, together with any others we may receive, for the consideration of our Corporate department.Does "together with any others we may receive" sound like an invitation?
Thank you for bringing your further comments to our attention.
Every little helps!
Here's your chance to do something — contact Tesco and tell them to start accepting Electron (they could do this TODAY).