Hopefully Wal-Mart will make new glasses for the boy free. I would speak to a manager about the situation and see if they are willing to do that. I assume the boy sustained no injury by wearing the wrong glasses, in which case you might pursue an injury claim.
I am not sure there's anything actionable here. Unless you can show damage to his eyes which is not correctable, it does not appear to me that this is case worth pursuing. Perhaps Walmart will consider helping you with the expense of the new parable glasses.
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Walmart should replace the lenses with the correct prescription at no charge. Speak to the manager. If he has suffered any long term damages to his eyes then speak to a local personal injury attorney.
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