If Altilly has been acquired by Qredit, there's nothing wrong with bothering them with claims. Looks like their site is still active.
https://www.qredit.io/altillyHere's how stuff worked on this exchange. Every user got a deposit address. Once a deposit cleared, a script transferred it automatically to their hot wallet which was used to fund withdrawals. Looks like they didn't have cold storage and didn't even have private key backups of that hot wallet (WTF really?).
Do you mean they use disposable deposit addresses? I'm just reassuring that they won't store every new deposit address of every user (especially if it applies to all coins) because that's a huge database unless it ends up burning. That's why they will deny ownership signed message verification because it's definitely useless. They failed at this.