Lest you think I'm just blowing smoke here: I happen to BE an attorney willing to take such cases on a contingency basis. It looks like an area with a lot of need to me, and I can't stand the idea of companies committing theft through incompetence.
Then let me ask you: How would you prove a case such as this one?
I come to you and say "I used to have 15 BTC in my Blockchain.com account but now the website says my wallet is empty and the address holding those coins has disappeared". You contact blockchain.com and they say "That never happened". Even if I can point to an address which has 15 BTC in it, I cannot prove that those bitcoin are mine, that that address belongs/belonged to me, that it was part of a blockchain.com wallet, that it used to be part of this specific wallet, and so on.
I can log you in to my wallet and show you an empty wallet, which proves nothing. Does this not just end up in a he-said-she-said situation of my word against the word of blockchain.com?