AIBU to ignore previous employer's request to repay overpayment?

[IOnlyHopeItsGoingGoingGone]

I worked for a company last year for 7 weeks. I was only there a short time because they were dreadful and my manager was even worse, so I cut my losses and left before it all started to get to me (which I knew it would, it was only a matter of time). So, I left in May 2023. During this time, I didn't get a full month's payslip, so had no idea what my normal monthly pay was. I was also put on emergency tax, so grossly overtaxed for what I did do. I'd also accrued some travelling expenses, which were due back to me, and took me a lot of chasing and over a month after I left to actually get. So it was all a bit of a mess, and I just wrote it off, put it down to experience and moved on. Anyway, a month ago (so over a year after I'd left) I received an email saying that due to an admin error, I'd been overpaid and that I needed to pay back what was owed as a matter of urgency. This was not a huge amount (around £100). They also insinuated in the email that I may have been aware that I had been overpaid (certainly not the case due to the reasons I mentioned above). They gave me 14 days to pay what I owed. I ignored this email. Now, a month later I've received another email saying that the matter is urgent and if I don't pay up within 14 days they will pass my case to their debt collection agency which may incur additional charges and affect my credit score. Would they really do this for such a paltry amount, when it's their error, over a year since I left the business?? Wouldn't it cost more in legal and admin to try and recover it than its worth? Are they just bluffing and AIBU to continue ignoring this? I don't even know if what they're saying is correct anyway!

I wouldn't pay anything until they could show me exactly where the overpayment was and removed what I had paid into for tax and other services on the amount.

Even if they indeed pay her 100 pounds more, it isn't that amount after taxes, etc. Not up to her to fix their mistake, if it is a mistake. Any company that so screws up their payments when employed would not be trustworthy now.

For those who wanted one, here is an UPDATE : The update is that there is no update. A week after I sent my email to their URGENT request to contact them, I have heard nothing at all! I was given a deadline to contact them (in bold capitals and underlined).... maybe I should've done the same in my email reply 🤔. I can only assume that it wasn't really THAT urgent after all. I continue to await a response 🙄.

It can’t effect your credit score as it’s not a credit agreement
its probably been spotted and part of their process is to request it, ie someone in payroll needs to show they have atleast asked you for it
I wouldn’t pay unless they evidenced and you agreed you had been overpaid
to be honest they are never going to take this further as would cost them more than £100, a year after leaving to be honest I wouldn’t bother responding

Also to add , I have just read where you went part time and therefore had a reduction in your hourly rate? Where you doing the exact same role just less hours, if so this is illegal as cannot treat part time workers less favourably- indirect sex discrimination as females tend to work part time more often than males , I would say they owe you money @IOnlyHopeItsGoingGoingGone

I would just ignore. I’ve had the opposite problem- tried to claim unpaid wages from a business owner that went bust. I've gone as far as I can legally pursuing the money for the past 2 years; still haven't received a penny. They can't be that desperate to pursue you for £100 (about a days work on NMW).