"Deduction" is referring back to the €150 deposit fee in the previous sentence. "Freezes" is what confuses me - I can only think that, if you use a debit card to pay the deposit, the money is immediately taken from your account, whereas with a credit card, you don't actually pay the money - then when you return the cycle, the deposit amount would be credited to your account, thus you'd never actually have to part with any money. I don't think "freezes" is the word I would use to describe this.
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