Bill - Not yet charged - Account Closing?

Hi, I was in contact with my energy supplier yesterday as they were going to increase the monthly amount. As a result I found they are not my Gas supplier and apparently Bulb is, I believe this may have been an error as they may not have taken back the account like they did with my Electricity.
I used the Uswitch service back in April however my supplier then was able to better their deal and as such I did not switch however it appears as though the Gas was switched. The result being I’ve had Gas since April and now I can only imagine I have a hefty bill to pay due to their incompetence.
Bulb has a banner on my account that states “Your account is being closed, and we’ll send your final bill shortly.” and I cannot see any bills.

What can I do as there is no way I can pay for 5 months gas supply, I need to feed my family and get to work and I can only imagine the bill would be something crazy?

Well, I got hold of my previous supplier and they have now taken back my supply, no worries here. Thanks any way.