A business service refunded double by mistake, should I have to pay back?

Question

For confidentiality, I'll have to be a little anonymous.
Basically, the business services of an organization I belong to, gave me the option that if I make any purchases with my own money I could fill out some forms to request reimbursement.

After a couple months I received double my reimbursement by accident. Here's the catch, they explained that due to a hole in their system, even though I was reimbursed, the system takes a while to process that information and so still labeled it as "needing reimbursement" which is where the second portion came from.

In addition to that, the second reimbursement, did not come in 1 form, but was broken into 2 partial reimbursement to my bank, weeks after the original reimbursement was given.

And due to sheer unfortunate luck, the second reimbursement time frame was the same as when I had returned college textbooks (you know how expensive those are). So with values being similar I had just assumed that was my textbook refund.

It wasn't until 2 months after that time, I received an email stating I was reimbursed twice and need to pay it back. However being in a tight financial situation, I don't have the amount their asking as of now, because apparently I had used it to pay gas and food bills.

Now I'm not a greedy kind of guy, and I try to hold high ethical standards. But honestly, realistically, I don't feel like I should have to pay, at the most, maybe half of what their asking.
Because while yes, I did use the money, it was unintentional. Had I known, I would have immediately contacted and questioned where the money had come from. Not to mention a part of this was their mistake as well and I do not feel I should have to pay for their mistake.

I could go on and on, but just to answer one question that'll probably come up, "Where did the refund for textbooks go then?" I had forgotten I used my credit card, and not debit card for textbooks, so when I checked my bank account and saw a refund I just immediately assumed that was it.

Answer 1

Yes you should have to pay it back, and legally the onus is on you to pay it back. The law allows for errors being made when paying/reimbursing people, and you are only allowed to keep money gained this way if you can prove beyond a shadow of a doubt that you had reason to believe the money was yours to keep and was not paid to you in error.

Answer 2

You know you have to pay it back. You were overpaid and everything else in your quesion is irrelevant. If they had not paid you would you be so lenient and easy about letting them keep the money. No of course not so why should they be happy to let you keep what is not yours. The fact you have spent it matters not. Pay it back even if you have to agree a payment plan with them to do it.

Answer 3

Grit your teeth and reimburse them back. You won't be paying for their mistake, you'll be paying for your mistake.

Answer 4

No.

Answer 5

lol, its not yours