We see stories like this often, OP. In this section, there are several similar ones. But the fact that you consider yourself honest looks different for the casino. The casino has hundreds of users; if your IP address once appears in the system, then you must understand that all other accounts that will be assigned to you will be considered multi-accounts. Talking about your personal reasons for wanting to stop playing or not for the casino will not look like a sense of understanding; if you want to leave, leave, but the site remembers everything. On the Internet, we are all creative, and it is very easy to tell sob stories, so much so that scammers show other people’s documents. But another point is that they don’t have to believe you. There is a record, and you can't do anything against it.
Even with all that, I don't see what I did to take advantage of anything? My original account was closed, I played on only one account this year, and I never used any casino promotions. Only raw balance I deposited was used.
I understand that it was my mistake not to try and reactivate my original account, but I am struggling to view this as justification for confiscating 26,000 euros.
And in terms of honesty, if this casino posts their evidence, at least it will show explicitly that I only used one account this year and no bonus or wagering abuse.