Final answer:
Zara should communicate the delay to customers professionally, provide an explanation and solutions, apologize, and assure resolution.
Step-by-step explanation:
In this scenario, the best action for Zara, the customer service executive, would be to communicate the delay to her customers in a professional and courteous manner. She should provide an explanation for the delay and offer any possible solutions or alternatives. Additionally, she can offer a sincere apology for the inconvenience caused and assure the customers that steps are being taken to resolve the issue and minimize future delays.