how to submit a two rate meter reading

How do I submit a two rate meter reading when the link only has one section to submit one reading?

This means that Bulb think you have a single-rate meter, when in fact you have a two-rate meter.

Contact Bulb using the information here to begin the process of correcting your meter information - https://help.bulb.co.uk/hc/en-us/articles/115001240291-How-can-I-get-in-touch-with-Bulb-