thanks Wingco39 for your reply, that is really useful to know re E7 and E10 not being interchangeable. I am slowly getting to the bottom of what might be making it particularly difficult to change suppliers, it turns out that the Our Power contracted engineer fitted our E10 meter, showed us the two tariff is on the smart meter etc, but then failed to update the national database of meters. As I paid by direct debit and didn’t see a final bill from our power, I didn’t realise that for the last year they have billed me on a single tariff! Three weeks in and I am still waiting for them to sort this out despite weekly phonecalls. So, I have a meter that is wrongly assigned on the national database so nobody can provide an E10 switch, and who knows how innacurate my bills for the last year meanwhile Utilitia cannot give me any information about what tariff I am on now at all. You couldn’t make it up. I’m going to take it up with Ofgem next.