One of the approaches we use to help with our quest of changing behaviour in organisations is helping to hire more people with similar traits to your best performers. 

This HBR article notes the shift required in customer service now that self service is the first port of call for 81% of all customers. This means that when customers reach your reps they have tried to solve the problem themselves and are already frustrated, making the call centre "more like a factory of sadness". 

The article outlines research that shows assertive 'controller' reps achieve the best customer satisfaction rather than the stereotypical 'empathetic' style of rep that most managers hire in those roles. It turns out that customers want firm guidance on the quickest path to the solution these days, rather than a sympathetic ear. It would be dangerous to switch to this strategy blindly for your organisation but it is surely worth a review of the behaviours that drive positive customer feedback. 

Picking your top performers, comparing against average performers and analysing the common behavioural and personality traits that differentiate this elite group, is a great way to test what succeeds in your specific culture and industry. 

The great news is you can both hire AND train for these differentiating traits and behaviours, which will help you make a rapid impact on customer satisfaction and resulting loyalty/purchasing behaviour. 

Be mindful that you will most likely have to shift management style and incentives too. Factories of sadness might cause some attraction and retention issues if your people practices don't keep pace with your customers' behaviour.