Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
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if you requested to begin the performance of services during the cancellation period , you shall pay us an amount which is in proportion to what has been performed until you have communicated us your cancellation from this contract , in comparison with the full coverage of the contract . 

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. OPTIONS: ["Contract by using", "Limitation of liability", "Unilateral termination", "Choice of law", "Unilateral change", "Content removal", "Arbitration", "None", "Jurisdiction"].