Complex English sentences 1?

I made a similar topic titled: "The complex English sentences ", and I'm still a few questions as follows:
"A new study out from Consumer Intelligence Research Partners estimates that between 300, 000 and 400, 000 total customers who would have otherwise left wound up staying with T-Mobile in the wake of the iPhone's launch on that carrier"

In the phrase "who would have otherwise left wound up staying with T-Mobile in the wake of the iPhone's launch on that carrier". "Otherwise" functions like? What does it mean that it is describing. Similarly the word "Carrier" bearing what is the meaning? I'm having difficulties in the complex sentence structure like this so I'm going to continue to need the help of those native English speakers. I would like to thank you.

You may be struggling with this because that paragraph is a bit wonky. It should read like this:

"A new study released by Consumer Intelligence Research Partners estimates that between 300, 000 and 400, 000 total customers, who would have otherwise left, wound up staying with T-Mobile in the wake of the iPhone's launch on that carrier."

Let's start with otherwise. The sentence is saying that there are customers who would have left T-Mobile IF NOT for the fact that T-Mobile became compatible with the iPhone. "Otherwise" is being used to mention an event that did not come to pass because of what happened.

Carrier is referring to the phone company providing service.

If I ask you, "Who is your carrier?", you may answer, "T-Mobile." or "AT&T"

Does this help?