Thank you for getting back to me!
Using your details, I've taken a look at your accounts for the period of 31/10/2018-30/1/2019. My findings are below:
For this 92 day period, you used a total of 2,456.271 kWh.
You were charged the the first rate for 1,026.031 kWh and at the second rate for 1,430.24 kWh amongst these three separate monthly bills.
Since my initial response yesterday, I've calculated that your threshold for the first rate is approximately 11.2 kWh per day.