I think the real issue here is communication, or in this case, lack of. It's not really enough to take orders and let the customer work out what is happening... If they had been on the front foot and put a warning notice on the checkout page that due to Dahl strike there will be delays, you have the option to not place the order. Then once ordered they could send out an email with confirmation of order AND advice on delays and expected ETA, with a general update every 2-3 days.
I work in sales, occasionally there are delays, but bad news is always better than NO news!