The structure of the charges can vary depending on payment method (by direct debit, pre-payment meter, or credit transfer such as cheque), on whether it is an internet-only tariff, which part of the country the customer lives in, if the deal involves a fixed price, when the deal was launched, how long it lasts, and so on.

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Telesales staff at Southern Electric, part of the Scottish and Southern Energy Group, mentioned the cheapest tariff in three of the 12 calls.

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This expansion and the valuations of the established Chinese makers was in part built on hopes that China would implement a German-style feed-in-tariff subsidy program, something China was talking about around the time of the Copenhagen climate meeting.

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States have leeway to decide how to implement the rules: ministers could stipulate a tariff above which prisoners forfeit voting rights, or allow judges to remove them as part of their sentences.

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