Twickets doesn't charge a fee to sellers, however please remember that PayPal's standard seller's fees of 2.9%+30p apply when using their service, which would account for any discrepancy.

In addition, the buyer would have incurred a Twickets buyer's fee for the transaction, detailed as "partner fee" on your Paypal statement. PayPal will then have transferred the Twickets buyer's fee directly to Twickets, so this is not a charge to the seller, merely a transferral of the initial buyer’s fees.

For more information on PayPal's charges, please click here.