Caribe Tours and Metro are possibilities. They would not deliver to homes, but to the terminals in the cities and towns where they provide service. People go to the terminal to pick up their package. People here are accustomed to do this and have been sending and receiving things this way for a long time.
What you would do would be to take the parcels you are sending to Metro or Caribe Tours. They would complete a form, which you would get a copy of. Insurance is available. You would need to let your customer know the bus line used and the parcel number assigned by the bus line. They would go to the local terminal, present ID, and ask for the parcel sent them, either giving the parcel number, their name,or both. The person receiving the parcel signs for it, so there is a record it was received.
I don't think you are going to do better than this for customers living outside Santiago, and this is established and people are accustomed to it.
In Santiago, you have other options. I'll let the people there tell you about them, but I am sure there are businesses now, like farmacias, that have delivery service.
