I'm curious what would have caused the pump to go out so soon. the trans in my truck (4l80e) was rebuilt back in 2018 when the PO still had it but doesn't have many miles on it. shifts hard from first to second like the line pressure is running full pressure all the time. wondering if that can cause a premature pump failure. I too have an aftermarket controller for the trans.
Are they saying it is NOT under warranty? Their warranty should cover any stock and aftermarket parts they had when they rebuilt it unless they said
“Replace part X” and you refused it back then.