If it's just clothing, I would use the post office.
I've recently shipped purchases (food products) with the help of my hotels in Italy and in Spain.
They help me pack it up--they provide a carton and the tape. (I always travel now with scissors, tape and some bubble wrap; but be careful if you are carrying scissors in checked luggage and plan to take the train).
The hotel packs it up and calls the shipper, which has been, in most cases, DHL. A carton smaller than a wine case, packed with jars of food, costs me a little more than 100 euro to ship to the US. I pay online, direct to the shipper.