Does anyone know how to get credit back from Bulb

How do Bulb reimburse any credit on one’s account if there have been no statements and no readings taken by Bulb and you decide to move to another supplier? I had £200 credit before smart meter fiasco started and continued with my DD’s, so assume I remain about £250 in credit.

My guess is that you’d need to supply manual readings to your new supplier as part of the switching process. These would also be used by Bulb to create your final bill.