As a normal rule you need to have a personal loss to have "standing" to sue. Under some circumstances you can seek an injunction instead of damages and may be permitted standing. Your facts do not permit much analysis.
The above is general legal and business analysis. It is not "legal advice" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.
However, fraud is a tort. Unless the target is a public entity, if the facts warrant you may be able to sue for punitive damages. In general, the measure of damages is how much it would take to make the defendant not want to do that sort of thing again.
See a lawyer. This is extremely fact dependent.
This answer is made available by the above lawyer for educational purposes only. It is also offered as a public service to give you general information and a general understanding of the law. This answer is not intended to give you specific legal advice. By using or participating in this site you understand that there is no attorney client privilege between you and the attorney responding. And, no attorney-client relationship has been formed. This site should not be used as a substitute for competent legal advice from a licensed professional attorney in your state. The information and materials provided are general in nature, and may not apply to a specific factual or legal circumstance. Only when a complete interview takes place is it reasonable to rely on legal advice.
You can sue for 5 gazillion million trillion dollars if you choose. The question is what can you realistically expect to recover if you win. Since you give no facts, how the dickens would we know what you can recover?
You can realistically sue for recovery of your damages and for an injunction and for attorney fees and costs. You will seldom recover attorney fees and costs, so you need to determine if your damages are sufficiently greater than attorney fees to justify suit or if you need an injunction issued to avoid further damages exceeding your attorney fees.
You don't have to be a customer, you have to be damaged by the fraud/false advertising.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.