transferred from TT Business to TT Residential
This seemed to happen quite randomly about two years ago. We had one direct debit payment account transferred, but not three others.
If you call TalkTalk Business they will transfer you back, but is similar to transferring from another unrelated supplier and you may have to set up the payment system again. You have to wait about two weeks and fend off the "please don't leave, would you like a discount" call from TT Residential. You will lose any fixed IP addresses (but if you have a technical problem then they get be converted to dynamic anyway -- that's how we discovered we had been transferred).
Biting the hand that feeds IT
