If there is a change to the Works Information then this is a compensation event. The Project Manager can instruct(not ask) the Contractor to submit a quotation. This could be something that is more expensive/more difficult, or to reduce scope/make something easier. Either scenario should be assessed as the time/cost impact of that instruction, and this can be a negative quotation i.e. a saving. If the Contractor submits a quotation lower than the PM believes it should be, then they can assess it the same way they can assess any compensation event and increase it accordingly. This is the rare scenario that the PM actually thinks the quotation is not high enough!!