I was wrongly transferred a referral bonus of 12k euros spanned across 10 transactions for a year starting Summer 2021 from my insurance company. I did not refer anyone however.
I reported the problem after the 2nd transaction saying that I wasn't expecting any money and I just got around 5k in 1 day as I did not submit any invoices for reimbursement or anything of that sort. The insurance company replied back a day later saying this is indeed my money and thank me for all my referrals. I just assumed someone was using my referral code and didn't bother to bring this up again especially when it's cumbersome to find an english speaking support agent here.
Fast forward, I get around 7k in 8 transactions in around 9 months bringing the total to 12k in 1 year (ended in Summer 2022). A week ago, I get a letter from my insurance company saying that they have found a glitch in their system and I was wrongfully transferred 12k during the time period mentioned above and kindly ask me to transfer it back as well as acknowledging that I reported this problem back in Summer 2021 but they weren't able to detect it.
From a legal point of view, what are my chances of keeping the money based on the above information?