There are THOUSANDS of books out there on selling and customer service skills, use them as a part of your coaching or training initiatives for access to great and inexpensive information. Have your team read 1 book a week, and require them to apply one new thing they learned from the book everyday. This one new thing could be a specific skill or technique, or even just a new attitude or way of looking at things.
Ask them to give you weekly reports on what they implemented, what worked and what didn’t. This interactive learning strategy could be done in two different ways. You could have members of your team read different books and then share the useful information with each other in group coaching sessions, OR have the group read the same books and let them discuss what specific things worked or didn’t work for each individual. Reading different books means the team can gather the useful information of multiple books in the time it takes to read one, while reading the same book then sharing with the group opens other team members up to new ways of looking at the same information they might have otherwise missed. Either is a successful solution.