How can this company still be in business!

After months of our efforts we have finally got Bulb to agree that they used the wrong figures to calculate our final statement. Today I received an email telling me we are £20+ in credit shortly followed by a demand to pay or they will escalate the matter to their debt agency! I so wish they went out of business.
IF I WERE YOU I WOULD GET ANOTHER SUPPLIER.

Hi @leavingyounow,

I’m really sorry to hear you’ve had issues with your account. I can see the account is now closed to £0 so you shouldn’t be getting any more messages about this now.

Georgie