Canceled T Mobile Wireless Internet and got charged $600

I canceled my T mobile wireless Internet because I went with Starlink and they immediately charged me $600 and told me that it's because I didn't immediately return it. It hasn't even been a full day and they charged me. Now they're telling me I'm going to have to wait for it to be received by their warehouse for the charge to be possibly removed from my account. Their solution was for me to just not pay my bill until it is removed which is wild because they would be charging me late fees and I don't need that BS