Your smart meter reading is from your small monitor that is called anIHD. These often give wrong costs and your bill is the important information. Check to see if your bill has been estimated and if it has send in the correct reading from your real meter - not the IHD.
@ ducat If you log in to your account, scroll to the very bottom of the webpage to the grey navigation bar, on the right you will see a link named 'complaints'. Click on that, and a new webpage opens, usually, the chatbox opens at the bottom of your screen to the right - green bar 'How can we help?' - though how long they'll take to answer is anyone's guess.