I thought they got 5% of the fee but nothing if they request a transfer.
Often there will be a loyalty bonus linked to the contract. If they are sold before the end of the contract without asking for a transfer they will receive the loyalty bonus they would have got if they'd stayed until the end of the contract.
Any percentage of the transfer fee would be something that had been negotiated by their agent, there's no rule about how much it would be, if anything.