Impossible to contact them

This is the company that an online shop I buy from uses. The first time they left the parcel at someone else's house, with the good luck that that other person contacted me and gave me my stuff. This second time I haven't been so lucky. I have bought some of my Christmas gifts to my children and I know tomorrow they won't be under the tree. I understand I have to pay duty taxes but they haven't sent me the invoice yet. It's basically impossible to speak to them as they don't pick up the phone and when I finally get someone they have the face to tell me they have tried to contact me, which is not true and they ask me for my ID and email address in order to send me the invoice, once again. It's 23rd today and I give up. This should have been an stress free shopping experience and I have spent too much time now. The direct number of the person dealing with my case and that doesn't answer the phone is ***