From Wilks' lambda, you know that your model is doing better than guessing, but you need to turn to the classification results to determine how much better. Given the observed data, the "null" model (that is, one without predictors) would classify all customers into the modal group, Plus service. Thus, the null model would be correct 281/1000 = 28.1% of the time. Your model gets 11.4% more or 39.5% of the customers. In particular, your model excels at identifying Total service customers. However, it does an exceptionally poor job of classifying E-service customers. You may need to find another predictor in order to separate these customers.