How to sell, higher price product in Category B and C Class?

1- Word of mouth 

2-Positioning

3-Payment facilities

4-guarantee

5- increase in the replacement time

Assuming here that Class B-&-C pertain to higher priced Products-&-Services, one way to handle this problem is to do as follows:

1. Understand one's target market (universe of prospects), their Procurement budgets and your Competition better

2. Know what high-priced procurements these prospects have made in recent past & why

3. Understand exactly what is the core problem(s) your Products or Services (or both) will address for each of these prospects and how critical is that core problem for each of the Prospects (these problems usually relate to Prospect's Topline or revenues, Bottomlines or Profits, Client-satisfaction or Market-standing, Employee-satisfaction etc.

4. Pitch your high-priced Products to those prospects whose lifeline (immediate or near-future) will depend your Products &/or Services.

By providing extra benefits on same. 

One should identify their need of product and recommend the product by the C category buyer

discussing with customer's business , discovering his weak points , trying to convince him by my product that will transfer his weak points to strong points and that will increase his profit   

By UR Efficient way of selling techniques