It's electricity meter reading exceptionally high

After being with British Gas for 19 years I switched to Bulb and was absolutely shocked when I received my first electricity bill . The meter reading, which I have checked, is stating I have used 6 months electricity in one month. I have a smart meter and my readings have always been submitted so no estimates. What I don’t understand is why the meter should go “mental” the first time I have switched. For the last couple of days I have been checking readings twice daily and it seems back to normal. Any advice please?

If you have readings from switch date and others you have taken I would contact Bulb direct to discuss on Monday.

Thank you. Will do.