Outfox the market only provides single rate tariffs, if you try to get a quote from them it advises that you would be charged on a single rate basis, however it offers 2 rate tariff via it’s sister company economy 7 energy (www.economyseven.co.uk) Outfox and eco 7 use the same advisers for both services so this maybe where the confusion has occurred in their reply.
Yes a manager confirmed Eco 7 will apply their usual tariff to E10 meters. Don’t be fobbed of by call centre staff, they might not understand what E10 is. I couldn’t get the one I first spoke to off the idea that E10 is always three rates. When I asked to speak to a manager all was sweetness and light.
I think Eco 7 are almost certainly the cheapest provider at the moment.