If after several emails sent to customer support asking if everything is ok with an order and if there are forecasts for shipping no response is received, some complaint from the customer is right and legitimate, moreover after 3 months have passed since the order.
Answers like "if someone is dissatisfied they can ask for a refund" sound intimidating and a little over the top, instead of using that tone it would be enough to reply to the emails sent by customers saying that there is some delay in the supply of the material and that the shipment has suffered delays.
A customer is always a customer, it doesn't matter if he is a video game enthusiast or if he is buying a book, after-sales support must always be present and guaranteed by the store.
Selling items is a business, leave the passion to the hobbists.