The project manager should do to communicate this message is to contact department managers who are identified as stakeholders, solicit concern, and provide updates to the situation. This is an example of the manage communications process, which involves ensuring timely and appropriate collection, creation, distribution, storage, retrieval, management, monitoring, and control of project information2. By contacting the department managers, the project manager can inform them of the issue and its impact on the project, and seek their feedback and support. The project manager can also provide updates on the status and progress of the corrective measures, and ensure that the expectations and needs of the stakeholders are met. The project manager should use effective communication skills and techniques, such as active listening, empathy, clarity, and transparency, to build trust and rapport with the stakeholders, and to manage any conflicts or issues that may arise.

Option A is not a good choice, because it is not the project manager’s responsibility to ask the vendor to identify the stakeholders affected, create an action plan and determine an implementation date. The project manager should have already identified and engaged the stakeholders in the planning phase, and established clear and agreed-upon roles and responsibilities for the vendor in the procurement documents. The project manager should also monitor and control the vendor’s performance and deliverables, and ensure that they comply with the contract terms and conditions. The project manager should not delegate or outsource their communication duties to the vendor, as this may create confusion, misunderstanding, or mistrust among the stakeholders.

Option B is not a good choice, because it is not a constructive or collaborative way to communicate this message. The project manager should not draft a warning letter to the vendor, ask internal stakeholders to comment, and solicit stakeholder support to hold the vendor accountable, as this may escalate the conflict and damage the relationship with the vendor. The project manager should instead use a more positive and respectful tone, and focus on the facts and solutions, rather than the blame and threats. The project manager should also follow the dispute resolution and escalation procedures specified in the contract, and involve the appropriate parties and authorities, such as the legal department or the sponsor, if necessary.

Option C is not a good choice, because it is not a proactive or realistic way to communicate this message. The project manager should not identify the worst-case scenario, put it into the project risk register, share the register with all project stakeholders, and raise an alert, as this may create panic, anxiety, or demotivation among the stakeholders. The project manager should instead identify and analyze the potential risks and opportunities associated with the issue, and update the risk register accordingly. The project manager should also communicate the relevant and accurate information to the stakeholders, and implement the appropriate risk responses, such as avoiding, mitigating, transferring, or accepting the risk.