Hi Dr D,
Not just you, that is poor service in my opinion.
The fact that you have paid for the postage ( i.e. not them ) is neither here nor there. Dynojet contract with Royal Mail (or whoever they use ) , not you, and so it is their responsibility to make sure the goods are delivered, not yours.
Keep on top of them and hopefully they will send another unit. If not, ask for a refund as they have not met their obligations under the purchase.
P.s. Have not heard bad things about them before ( quite the opposite in fact ), so perhaps this is just a one off !