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How much would you invest to prevent a mass customer exodus? Everything Everywhere, the merged T-Mobile / Orange behemoth, was happy to spend £150 per customer to shore up its customer base following the post-merger restructuring.

What did it gain? A reduction in monthly churn from 1.7% to 1.3%, significant given their customers number well into the millions, plus an additional 300,000 customers locked into long-term contracts in place of short-term pre-pay contracts.