Grounds to sue Coinbase?

Coinbase lost buy records of a cryptocurrency I bought (presumably because they delisted the coin) and I now I can't take thousands of dollars worth of long term capital losses because I don't know exactly how much capital loss to take because I don't know what price I bought the coin at (and the coin is now at zero).

To be clear, these are records coinbase has for other coins which are not delisted which is why I am assuming that the fact that the coin was delisted must have been what confused their system.

Complaining to the CFPB did very little. Coinbase credited my account $100 because "this isn't their normal customer experience or something" but this does very little to compensate for the lost records. The only records which are really available are records which show which day the coin was bought but, the price fluctuated wildly on that day so, that really doesn't help either. The loss, based on that, could be between like $500 and $30,0000.

As far as I know (and have read) they're violating various financial laws in not having these records available. The original trade was only from about 3 years ago.