Powersource Josh - The salesman Shipped wrong product, SLOW shipping on replacement, Refused to process Core Return. Internet

I needed a new transmission for my Windstar and wanted one rated for towing.  After a long search found Marshall Engines. 36Mo/100K warranty and rated for towing.
Talked to :
Michelle Self 
Customer Support Rep 
Marshall Engines 
1-888-236-9610 Ext. 128 
She refereed me to Powersource ( a re-seller) to purchase the unit at a bit of a discount.

I talked to Josh at Powersource- 901-834-5278, and ordered the part.
It took about two weeks before I was contacted by R+L Carriers that the part was in and they would delver it. Then we had a snow storm, and the delivery was delayed an additional week. It just showed up one day when I wasn't there, they never contacted me to tell me it was being delivered. 

I had arranged to use a service bay to install the transmission, so I had my car towed to  the shop that evening. Upon opening the box the next day,  I realized they had sent the wrong part.
I called them and told them the problem and it took 3 days for them to admit they sent the wrong part and said I had to call R+L Carriers to pick up the wrong one. I called the carrier and 2 days later they showed up. The driver had no paperwork or idea what was going on. I filled out a shipping form and they took away the transmission.

A week later, I was told that they were processing the return as a warranty replacement and they would send the correct part out soon. 
It took another 2+ week to get the correct part and by that time I had lost access to the garage I was going to use. 

After a few months of arranging to get a new work space, I gave up and paid a local shop to install it.  An additional $900, a months I would not have had to spend if they had shipped the correct part in the first place, or had shipped the replacement as soon as they knew they had sent me they wrong part. 

After all that I contacted them about shipping the old one back and getting my core charge back.
I was worried that it have been a long time, but was told by Josh:
"We don't have any time constraints on core returns.  I'll just need your information to get the core pickup done.  I remember selling it to you, but I don't recall all of the pertinent info."
I send him all the info, including scanned copies of all the documents, and got back a message:
"That'll get it done!  I'll get everything in the works for the pickup.  Thanks, Josh"

I never heard from him again, no response to calls or emails. 
I contacted Michelle Self and Kelli Lawrence at Marshall Engines, but didn't get any response from them.

So I'm out the additional time and $900 to get the transmission installed, and $400 for the core charge.

I'm a bit worried that the 3mo./100K mile warranty might be useless, since the "customer service" has been so bad so far. I suspect that if the Transmission does fail, I'll just have to go to court.