Is this store OWNED by AT&T (just because it says AT&T on it doesn't mean it's owned by AT&T; ie., The store's sign could say, "AT&T Authorized Dealer" and somewhere else, it'll say "owned by xxxxxx") If this is the case, simply go to a different store, because any AT&T owned stores have a much higher customer satisfaction.
You can post your reviews... somewhere like "Google+ Reviews", or "Yellow Pages", or "Angie's List"
To be quite honest, I just think you're slightly overreacting and you can easily go to a different store, or even talk to the manager of the store.
You may also want to check your account for any Early Termination Fees or Contracts that you may have.... Paying two early termination fees can cost upwards of $300+ a piece, and those fees won't be waived for "upset customer" or "bad store experience".
______________________________________________________ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ Former AT&T employee
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