Switching from E-On to Bulb

Recently I switched from E-On to Bulb and paid last Month to E-On and now I’m billed by Bulb a few days after .
Why this payment from Bulb was taken in advance ?

Recently I switched from E-On to Bulb and paid last Month to E-On and now I'm billed by Bulb a few days after . Why this payment from Bulb was taken in advance ?

This page should explain it: Why is my old supplier still charging me? – Bulb

It is Bulbs policy to take 1 month in advance, you would have been given details of this when you switched.
that aside E-on will continue to take their DD until the final bill is sorted. You wont however pay for your energy twice as any credit will be paid back by E-on.