-snip-
Is this your solution when you said you stand by your first reply?
No, since it's an online wallet, even though their wallet is deemed self-custodial, there's little to nothing you can do if there's an issue with the wallet file itself.
So if their suggested manual export of the private keys from the wallet file via btcrecover doesn't help,
The only solution left is to communicate with their technical support (
which will be a big problem considering their track record)