@Glitterpop88 How long was it between when the first direct debit that should have been paid wasn't and when they notified you that it hadn't been? Scottish Power like to send messages to your online account concerning things like this, but as messages there don't trigger your main e-mail there's no way you'll know you've got a message unless you sign on to your account and go look yorself. So they might have advised you the direct debit hadn't been paid long, long before you received a message in your main e-mail. Even so, did you not see on your bank account statement it hadn't been paid out?
If a missed message is the case, they'll want to know why you didn't check yourself and make arrangements to pay monthly. They'll also want to know why it took you until the middle of the year to tell them you weren't being billed for any electric usage. Unless you've got good answers to those questions it would probably be best to try to resolve the problem with Scottish Power than take it to an outside resolution centre, who'll probably not be sympathetic with you. Open a new complaint, as it's a new issue, but be ready for those difficult questions.
@Glitterpop88 Bit confused now. How can someone at SP have had to "go right back" and keep you waiting "7 weeks" if the first direct debit was only due out this month? I would have thought the size of the direct debit taken would have told you if there was only one or both energy supplies taken.
Neither would the fitter tell you you need to check your bank account to make sure a direct debit setup had been accepted and actioned by your bank or the payee - outside of his remit.
@Glitterpop88 That's what I thought. That's why I suggested you check back in your online messages to see if and how long ago they advised you they hadn't been able to take the direct debit. SP have limited access to your bank account arrangements so the onus will always be on you to check the new DD you'd set up was taken. (DDs are 'taken' by a payee, as opposed to standing orders, which are 'sent' as it were.) So there is an out for you, if you can show the new DD was set up, but SP just didn't 'take' it, or that you weren't advised they were chasing the wrong one.
There's a notice period of 10 days payees have to give before changing any DD they're due to take (date or amount), I believe there's also a grace period for payers to change details of a new DD setup. Putting you straight on to quarterly cash the very same month a DD fails to pay is unwarranted - especially so if they hadn't advised you or advised you late that it hadn't gone through. That might be your best angle for your complaint.