If the Contractor disagrees with the Project Manager's response/decision, what actions in within the contract can be taken?

If there is disagreement between the Contractor and PM on matters such as compensation event disputes or retained delay damages, what available options are there for the Contractor to take?

The answer depends slightly on the version of NEC3/4, Z clauses and secondary options chosen by the parties. Check which options are selected in the contract data.

Typically you will need to follow the dispute resolution procedures (W options e.g. adjudication, mediation, litigation or arbitration). You may find that there are z clauses that encourage a senior representative meeting, etc.