Dunning letter functionality after upgrading to R12

Oracle APPS 11.5.9 we are using Dunning letter functionality in Receivables. Some Orgs are using different sets of dunning letters for different set of customers. Example :

·         ABC citation dunning letter set is attached to ABC Collections customer profile class.

·         XYZ Standard dunning letter set is attached to XYZ Collections Customer Profile class.

Org ABC,  Customer have customer profile classes attached with the customers. Some customers have been assigned "ABC Collections" customer profile class. And rest of these customers are assigned "XYZ Collections" Customer Profile Class.

These Customer profile classes dictate which customer will get which dunning letter.

Q1. How can achieve the same functionality in R12 Collections?