Anna, you also have a limited amount of time to use the credits. But if you have 2, you can only choose what you have or less. If you pick 3 then it will charge you for 3 and not use the 2 free credits first. Hope that helps!
After you swipe your card choose Review Reward. The next screen will show credits. Back out of that screen and choose the single 9minute cycle button displayed. That 9 minute cycle is free. You'll be surprised how good that single cycle does. I'll run a free cycle. Pull the dry stuff then run another cycle @ 33cents then I'm done.
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