Sounds like possible breach of contract, but I wouldnt be surprised if the contract doesnt give you the option to switch the card provisions, when the credit card is closed. Read the small print, before you draft your suit. May want to consult with atty familiar with consumer protection laws involving credit cards etc.
You are correct that unjust enrichment is usually considered a remedy, not a separate cause of action, under California law.
If you did not receive benefits, you might have a cause of action for breach of contract. You might also have a claim for unfair business practices under Business & Professions Code section 17200 et seq. (but you won't be able to recover monetary damages for a UCL claim). However, there is insufficient information in your post. It is quite possible you might not have a viable claim against the bank holding your HELOC if the bank had a contractual right to close your lines of credit if you were in default under the loan. I think more information and analysis is needed.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This Avvo.com posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, please consult with your own attorney.
I must part company with Mr. Chen on this one on very technical grounds. Unjust enrichment is neither a remedy nor a cause of action but an element common to several causes of action known as the common counts. The remedy is restitution.
If the bank actually took money from you wrongfully, the cause of action is "Money Had and Received." You would show that the bank was unjustly enriched by receiving and retaining money that in equity and good conscience belongs to you. You would ask the court to restore the money the bank took.
In any event, you would only add a common count to your cause of action for breach of contract.