Atrocious service

Ordered 2 items which we meant to be delivered on a Monday as I would be home all day,tracked the parcel around 13:00 and it said the parcel has already been delivered,I made contact with them on e-mail to notify them that I hadn't received the parcel but till today I have not received any answers from them. 4 weeks has passed and they refusing to refund me,I don't even know what to write on e-mail anymore as I can even tell that the responses I am getting are automated one's.