Why are you still complaining 
You now have three different integral values, so you can choose the one you like the most 
Using “ROOT::Math::IntegratorOneDimOptions::SetDefaultIntegrator(…);”, you could try all different available ROOT’s “1-dim integrators”: “Gauss”, “GaussLegendre”, “Adaptive”, “AdaptiveSingular” and “NonAdaptive”. 
You will then have six different integral values to choose from
BTW. ROOT’s “integrators” are well known to misbehave in all cases when the function “changes rapidly” or if there are “narrow / sharp peaks” inside. I think that, in vast majority of cases like yours, people “blindly” use the returned “integral” without noticing that it is wrong. What’s even worse, “integrals” are quietly calculated and used internally by some methods in various classes (users may not even realize that this happens).