I'm looking for a study or any materials stating how much each type of contact cost in average. Like:
1 call = 6$ (or€)
1 web chat = 2$
If the study also describe how many contacts are necessary by channel that would be great. For instance we know that eMail cost less than a phone call but generally you need several eMail to solve an issue, making the eMail in the end more expensive than a phone call.
Looking forward to reading your insights!