Once it’s resolved, I’d also like to come back here to explain a bit more about what went wrong, and the steps we’re taking to make sure it doesn’t happen again.
Alright, here’s a bit of a debrief on what happened and what we’re doing to prevent it in future. I’m going to keep it general rather than address the specifics of any case 
We offer several plans to help people manage their overdraft
Sometimes this is because folks are experiencing financial difficulty, but it can also be to provide some structure when they want help to reduce how much they’re using their overdraft 
Each of these plans is powered by a schedule of ‘target balances’. E.g. you might have a plan that reduces your limit in £50 increments, and looks like this:
- Today: Limit of £500
- 01 Oct: Reduce to £450
- 01 Nov: Reduce to £400
- Etc…
We generally set these plans up to start from either your current overdraft usage or your overdraft limit, usually based on what you ask for. But sometimes there’s confusion, or we make a mistake and use the wrong starting point.
We’re doing two things to make this better in future:
- In the immediate term, we’ve reminded COps how important it is to make sure we use the right value
- We’re also planning a small improvement to our COps tooling in the next few weeks, to help COps choose the right starting value every time
We found a bug recently which stopped some planned reductions happening
This was unfortunate. Normally we would have received alerts as soon as this went wrong, but in this specific case these alerts were suppressed, so it took us longer to realise this was happening than we’d have liked 
When fixing this bug, we decided to apply any reductions that were due on active plans while the bug was present.
Unfortunately, we didn’t account for plans that were:
- Set up incorrectly
- Active while the bug was present
- Subsequently cancelled
This meant - in a very small number of cases - we reduced limits according to a now-cancelled plan. It was “technically” correct, because the reduction would have happened were it not for the bug. But it was definitely not the right outcome for people in this situation and we’re very sorry for causing these customers any stress and confusion 
We’ve already changed the part of the system that reduces limits, to make sure it won’t do so again if a plan is not still active 