If you are worried that your order is not going to arrive on time, or ever, it's time to react. First, contact the seller. If there is no response in a few days, contact Amazon directly.
Amazon will always refund you your money once they have verified that the seller is a scammer. But this might take weeks. Instead of waiting all that time, if you can, oder the product from a trusted seller on a second order, and get the refund for the first order after Amazon approves it.
How to contact Amazon directly: