Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
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service contracts : the cancellation right expires earlier if the service has been fully performed by us , the performance of the service began with your prior express consent , and you acknowledged that you lose your right of cancellation once the contract has been fully performed . 

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