Channel Tunnel operator Eurotunnel is facing a revolt from haulage companies over plans to increase its prices.
Lorry firms are threatening to switch to ferries over the tariff change
Under a new pricing regime from 1 January, it wants hauliers to forecast how much they are likely to use the service over a 12-month time span.
If lorry firms send too many or too few trucks through the tunnel they could incur a charge of £750 - up to four times the current rate for each trip.
Tariffs of about £200 a trip will be rewarded if their forecasts are met.
Eurotunnel said it would allow for an error of 25% in predictions before introducing the top rate.
Dirk Broek, director of Eurotunnel's Freight Division, said the objective was to improve the quality of service by "better aligning capacity to customers' demand".
He said the response from customers had been "very encouraging".
However, lorry firms are threatening to switch to ferry services if they are made to predict their likely travel through the Channel Tunnel.
Mike Beer, who runs a haulage firm in Dover, said the new system would be no good to his company.
"Almost every haulier I've spoken to that has been approached has said as from 1 January it won't be any good to them and they won't be using it."
Eurotunnel journeys for lorries could rise to £750 per trip
He said Eurotunnel should be working "in partnership" with hauliers, rather than "working against them".
Eurotunnel, which has debts of £6.4bn, said its change in policy would enable it to run fewer, but fuller, trains if it knew in advance how many lorries would be heading through the tunnel.
A statement said: "We're confident that it delivers the right mix of benefits for the customer and cost savings to grow our business in 2005."
But Donald Armour, of the Freight Transport Association, said Eurotunnel should be "offering incentives", rather than "penalising" customers for not meeting their predictions.