It all depends - how much do you want to spend?
We do ours in-house, but:
For service,
http://www.customerfocusinc.com has a good program. Ask for Steve Fugate.
For service and sales,try
http://www.progressionsinc.net For a more comprehensive program, CohenBrown, but be prepared to spend the money.
Please note, as I said - our S & S training is in house, I do not work for nor have I purchased from the above mentioned vendors.
For a longer list, please send me a pm.