Ignoring the estimated readings and just using your accurate readings, that shows a usage of 827 kWh used between 25/02/19 and 28/05/19. That's an average of 8.99 kWh per day over the 92 days.umm let me re-read my bill again:
Period :25/02/19 until 31/02/19
My Reading: 28172
Estimated: 28510
Electricity united used: 338 kWh
kWh rate: 16.02
Period: 01/04/19 until 28/05/19
My Reading: 28999
Estimated: 28510
Electricity units used: 489 kWh
kWh rate: 18.24p
It's more concerning your bill shows a date of 31/02/19? I'm pretty sure February doesn't have that many days.