You may have a claim for fraud against the company that deducted a larger amount from your account than you were quoted.

Since this is an online company, you will need a physical address for the company in order to file your lawsuit because the lawsuit will have to be served on (delivered to) the company.  If the company does not have a physical address, the company may have an agent who can accept service of process (delivery of the lawsuit).  The address of that agent will be necessary in order for a process server to serve the lawsuit on the company.