Stripped Oil Pan and Plug with a helicoil that fell out!

Ford mustang

I've recently had it out with the local ford dealership. They have always been the ones to do my oil changes, and the other day I took it to this guy in my town to have it changed because I didn't have time to go to the other place. He found that someone had put a heli-coil in my oil pan because apparently someone thought I had stripped threads. The thing fell out with the plug and the plug no longer stays in. Only place I've been to is Ford and they swear up and down they never use this to correct a problem. I have done my research. Ford said they charged $75 to put a helicoil in so I'm wondering if this is correct? The heli-coil came out with the oil plug and isn't that suppose to be secured and locked? This has also been done recently because the guy I went to the other day I had went to a couple months ago. He said this was the first time he had ever seen a helicoil used and he would have noticed it before. I know for sure it wasn't him because I watch him and talk to him while he changes my oil. However, dealerships won't let you stand back there to watch. So I've done pretty much everything I can do, called the complaint hotline interrogated him which that led to some interesting things like I had an oil leak which was never told to me but its in their computer! So seems like a good reason to put a helicoil in other than they stripped the thing themselves. I was also told by other places that it sounded like a cover up. I mean I can go on and on with this. I'm just wondering are there dealerships or places that put this on without the consent of the owner? I've got a rubber plug in now so its fine for now. But I will never buy another Ford and I will never take a car there to get it worked on again. I mean I'm just trying to get into the mind of an asshole and its kinda hard to do so does anyone know of this happening. And I also think its weird with everything else they try to get me to have done to my car that they wouldn't have told me to buy a new oil pan to make money off of me. My damn check engine light has been on for 4 years straight and they still tell me every time I walk in that I need to have it checked. All Ford said they would do was look at it, ya know, I can look at the damn thing all day long but it isn't going to fix the shit. Just because I'm female they tell me anything. Hopefully that will be a slap in the face.