Switch from British Gas to octopus

TCMUllane

a few weeks back i switched to Octopus from British Gas i have the old key and card meters so we went threw formalities i asked if i could have smart Prepayment meters to my shock i was told no if you want one you have to have a direct debit setup i told them no i dont want that i want prepayment smart meters was told no again the young lady i was talking to kept going away and coming back with every question i asked her. So now the the bit i need your advise with on my electric meter i have over £200 and gas £600 now what happens with that money now i switch will it stay on the meter and i can just use it till it runs low but then if i dont top out Octopus will start charging standing charge debt any advice would be helpful