Tub Drain

Hello,
I just joined this site and I'd like to say hello to everyone. In no way should I be considered a plumber so please keep that in mind when you read my question I'm in serious need of some expert help. I live in a small apartment by myself and yesterday I tried putting in a new "Foot Lok Stop Drain Assembly" in the bathtub because calling one of the maintenance guys is about a three-month wait. The threads in the flange part that the pop-up screws into were stripped so I bought the item I listed above at the local Lowes store. I asked the plumber in the plumbing section how would I go about changing the entire unit and the advice he gave me was to put a Crescent wrench between two of the crosshairs and then use a screwdriver in the hole at the top of the wrench. After putting the wrench in and I tried turning it, the crosshairs broke and now I just have an open hole without any type of drain. I had one of those rubber stoppers so I'm using that for now, but I would like some advice on how to go about removing the bottom portion of the drain(flange part)? I'm afraid if I can't replace the unit I'll end up buying an entire tub assembly, including the surround because it's all one piece which i don't want to have to do!! Any help would be greatly appreciated. Thank you

First off remember that most of the times those guys at the hardware are not real plumbers, but that is a way to spin the drain out if you dont have the correct tool. They do make an internal wrench for those after they break. I believe they carry them on amazon or the hardware has them

Search internal pipe wrench on amazon

Tub drain removal tool