The graph uses the phrase “High Promotion” which indicates customers attracted by a deeper price cut. “Low Promotion” means an offer to join the Telco but with a shallower / less attractive initial deal.
The story is not all bad. The company attracted some additional customers with a deeper price cut. And some of them did stay. This is probably because the deeper price cut attracted some buyers who might have bought anyway; as well as some more price-sensitive buyers. But on average, the deep-price-cut buyers migrate away at a higher rate.