If the PM incorrectly rejects a compensation event notified by the Contractor (late response of a design design submitted in accordance with 21.2) , what can the contractor do if the consequence of this event delays and disrupts the Contractor providing the WI.
Unfortunately the only recourse that you have as a Contractor is to go to Adjudication. If you do not get this agreed that it is a compensation event, there is no mechanism to move the Completion Date and if you achieve Completion beyond the Completion Date you will not be able to recover additional prelim type costs and you will be liable for delay damages if X7 has been included within your contract.
On a practical level you obviously need to try to convince the PM that it is a compensation event, but if not your only official recourse is for an Adjudicator to look at the principle as to whether it is a compensation event or not.
Notwithstanding the advice above, you might also wish to check that the client hasn’t introduced any alternative dispute resolution provisions via Z clauses. These typically kick in before adjudication, so you might be obliged to meet with senior representatives or hold a mediation meeting before you start adjudication. A risk that I highlight to Clients (and over zealous PMs) is thats these issues can be left too accumulate until the end of the project and the Contractor can start adjudication at the end of the project. Is this really in the Clients’ interest?