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.
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As Mr. Doland notes, you do not provide details.
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.
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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.
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