Best answer by woz
this isn't a PP issue it's an industry issue, and paying more than one supplier, sometimes for one, two or even 3 months is sadly (to quote Sir Tom) not unusual. Your final bill should be produced in 6 weeks.
You haven't had problems joining PP as you've clearly joined, but what you might want to do if you're in credit with your previous supplier is contact them and ask them to reduce your DD to a minimum or suspend it until you get your final bill. If you cancel it they won't know where to refund. Also if you are in lots of credit you could ask your bank recall one of the DD's which went to your old supplier.
Your figures don't make sense, if your PP payment is £66 a month (which seems very low for a winter payment) I'd expect your old suppliers payment to be similar or perhaps slightly more - how can you be paying £66 to PP and £160 to your old supplier unless it was 2 payments in one month?
Once you get your final bill from the old supplier it will be resolved but you won't be paying for the same energy twice.
Did anyone have problems joining. So far I've made 2 payments to Pure Planet and 1 to my previous provider. The change over is still not finished so I will have to make another payment to the previous provider. Instead of paying £66 a month I paid £226 last month and who knows what I will pay at the end of the month.