I had an induction cooktop (aka glass top) and hated it. You can’t use cast iron cookware on it. The temperature won’t stay stable. Then the power control (knobs) started failing. The temperature would runaway. Luckily I was in the kitchen each time it happened. If not it would have probably caused a house fire. I didn’t dare leave anything simmering if I wasn’t in the kitchen. By the time I replaced the 3rd controller I could have almost bought a gas stove. The glass top is also hard to clean and scratches. They are for people that don’t really cook much.
Wow! You must have happened to get a really bum one.
We often use cast iron on ours. It works really well with cast iron.
I don't know of anything you could have done wrong to not have been able to use cast iron.
We have had none of the problems you described in many years of heavy use of ours.
What brand?
Ours is a Kenmore Elite.