Most libertarians agree that fraud should be illegal, and that customers should be able to press criminal and civil charges if fraud is perpetrated against them.

In this case, the bank charged customers for services they never requested. That is fraud. It has nothing to do with "free markets" as defined by libertarians.

If you find some libertarian scholarship, you will also notice that libertarians see contract enforcement as a vital role of government. This would also be a breach of contract.

Libertarian != Anarchist :)