come again?

I studied with a new English tutor today.
I didn't understand what she said. So I said, "Come again?" and she said it was a wrong expression.
Maybe she felt bad because it was her first time seeing each other and it was informal.
She asked me to say, 'Pardon me?'
Most of her students say so.
I don't like the phrase 'pardon me?' for some reason.
I don't know why.
She doesn't like the word 'come again?' very much, so I'll just say 'excuse me?' or 'i'm sorry?'

I studied with a new English tutor today.
I didn't understand what she said. So I said, "Come again?" and she said it was the wrong expression.
Maybe she felt bad because it was their first time hearing each other, and it was informal.
She asked me to say, "Pardon me?"
Most of her students say so.
I don't like the phrase "pardon me?" for some reason.
I don't know why.
She doesn't like the word 'come again" very much, so I'll just say, "Excuse me?' or "I'm sorry?'