3.13 If the Department consider that a service is not delivering value for money, despite the Variation of Prices formulae, the contract allows them, in exceptional but undefined circumstances, to undertake a "value for money challenge". Under the terms of the contract, such challenges can be mounted a maximum of three times for each service over the ten year period. A value for money challenge would involve benchmarking BT's prices against market comparators in order to demonstrate to BT that they were not providing value for money. The Department would then have to obtain BT's agreement to reduce their prices for that service, or otherwise improve the value for money of the service.