I don't think this follows from the stated figures!
12KWh * £0.12354 * 1.05 = £1.56. If you'd like the standing charge included, for me that adds £0.015/KWh, making it more like 12KWh * £0.139 * 1.05 = £1.75.
You'd be paying something like £0.54/KWh to make it £6.80! - perhaps it costs that much in the Shetland Islands, but this is out of line for most of the UK. You can pay more than £0.12354/KWh, but not THAT much more. I'd advise shopping around.