IHD No Longer showing correct usage cost

Since the 1st of April the usage cost of electricity on the IHD is consistently 50p below what it says the usage cost is on the website the next day.
Before the 1st both Gas and Electricity usage shown on the IHD agreed within 1p of what it said on the website next day but now the gas is correct but the electricity is consistently 50p more on the website the next day than the IHD shows.
The history on the IHD also still shows its reading 50p below what the website says.
Which one is correct and if it’s the website, what is the point of the IHD if it does not display the correct cost each day.

Same problem here.
Went to bed last night and looked at IHD expecting usage to be about £5 for both at end of night
Had a look on website usage this morning and its stating just over £7 total for both
I am thinking there is a £1 difference on each
will be taking photograph of IHD tonight