changed supplier

I changed the electricity and gas supplier for you, and do I have to call the old supplier and let them know that I change them, will you inform them for me

I changed the electricity and gas supplier for you, and do I have to call the old supplier and let them know that I change them, will you inform them for me

Does this Bulb article answer your query: https://help.bulb.co.uk/hc/en-us/articles/360016445831-What-happens-when-you-switch-to-Bulb