Starbucks literally probably has the best service policy. If you're unhappy with your drink and polite about it they will 100% do everything they can to make it right. Next time maybe ask them to fix it instead of posting on Google where no one can help you. If your drink is normally made with foam, it's also possible that it's just melting before drink it which would give the illusion of not full. This would apply to most espresso drinks like lattes, machiatos, and cappuccinos. If that's the case, try asking for light or no foam :)
If your cup is not full, ask them to fill it.
I never have this problem.
It depends on what you ordered. Also if you are not happy with your drink let the barista know, they will be more than happy to make you another.
Always will redo if you ask them, never had a problem.
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