T-mobile asked me for my PIN over the phone

I wanted to change plans and have it activated the same day, which required that I call them directly. They said that they could only "open" my account with the PIN and I had to verbally tell them my PIN. I thought this was a security issue and told them that. Their response was, "sorry, no can do." Since I didn't know what my PIN number was, they issued me a temp number, and required that I give them a new PIN number over the phone, right after they issued me a temp PIN. Isn't this considered a bad practice? I'm not a security expert, but have always been told not to give out passwords/PIN over the phone to anyone.