They've made their own assessment and it's far too low

NEC only lets your main contractor make its own assessment of an event in limited cases. It can do so where no quotation arrived in time, or where it decides your quotation was wrong and does not ask for a revised one. It can also do so after a programme failure the contract names. Once notified, its assessment is implemented, which means it becomes the agreed change. The way to change it then is the subcontract's dispute procedure, not another quotation.

Own assessments tend to cut the same things. People are priced below what the records show, equipment hire is shortened and forecast cost is ignored. The Fee is applied to less than it should be, and a bare figure comes with no details.

Each cut can be tested against the Schedule of Cost Components, the contract's list of what counts as cost, and your records. But resending the original quotation tests nothing, because it no longer has any standing, and the low figure stands.

Take the assessment apart line by line against the cost rules and your records: which people, which hours, which equipment, what forecast and what Fee. Compensation Event Claim rebuilds the event from the Schedule of Cost Components. It separates the wrong cuts from the fair ones, and prepares the reasoned answer in your name.

If agreement fails and the difference justifies it, the rebuilt figure becomes the money side of an adjudication under your subcontract. Compensation Event Loss Prevention then makes sure future quotations go in on time and in the contract's cost shape. That removes most of the grounds for an own assessment.