Is my transmission completely gone? Or should I get a used one?🤦‍♀️

What is your question?

Okay bought this Jeep 3 months ago I had it checked out beforehand professionally, I put $3,000 into it since and now my transmission whines up really high and then down and I'll be going down the road and all the sudden I lose all power I step on the gas and it doesn't want to go and then it will go. It makes a knocking sound also. The holes subframe was rusted out on the inside not the outside which I definitely don't understand how it can even do that. I don't know what to do I don't have the money really to put into it but I was wondering also is there only one size of transmission that fits this type of Jeep Compass 2011? I'm told I should just sell it to the junkyard please help!

What makes this problem better or worse?

Nothing

How long has your 2011 Jeep Compass had this problem?

no power 3 weeks