National Tire & Battery [NTB] review: diagnosis of starting problem-wrong diagnosed

On 6/20/2019 I took a 1999 mercury villager to ntb in hixson, tennessee.
First diagnosis
They diagnosed the problem as being a bad fuel pump. So we purchased a fuel pump from o'reillys auto parts. And ntb claimed it was a bad fuel pump. So we exchanged pumps and they diagnosed it to be the sending unit not the pump. They said they could not find a sending unit or pump. So I ordered a sending unit and pump from amazon ($185.00). After 5 days of waiting they said it was not right unit. (I even showed ntb picture of unit before ordering)
Second diagnosis
The manager said that we needed a distributor. ($682.98). I asked the manager if he was sure this would cure the problem. "I guarantee it" he said. After paying him $682.98 and 5 more days, they finally pulled the van around and it had a ping sound. So we drove the van and it still wasn't fixed.
Third diagnosis
It definitely was the fuel pump or sending unit. And he would repair it for another $300.00 then he dropped price to $200.00 labor. (so I drove 200 miles and bought the third pump and sending unit.)
After this the manager became scarce and refused to wait on us.
Also I noticed that since the begining, 2-3 different mechanics worked on the van.
After returning with 3rd fuel pump, a mechanic took 10 minutes to install. Pulled the van around. By this time the engine was really clanking. I asked the mechanic why. "he replied that it could possibly be a knock sensor, but didn't really know. I asked for the manager again. I was told he was off again, they didn't know when he would be back in.
After not seeing the manager, I was told that he would not charge me for installing the third pump and sending unit. Van was making a lot of noise at this point.
Fourth diagnosis
After leaving ntb I took the van to express auto on 1916 gunbarrel road.
Diagnosis was a rod knocking. So we ended up putting a new engine ($999.00), labor ($932.00) the original problem the van was idling and dying.
Total spent
Ntb= $682.98- distributor parts & labor)
Parts=fuel pump $109.00 (o'reillys)
Parts=fuel pump and sending unit - $185.00 (amazon)
Parts=fuel pump and sending unit - $55.00 (used) turner auto parts
New engine=$999.00 (sv engines)
Labor for installation of engine. $932.00
I feel like I should be re-imbursed for new engine (parts and labor), since when the van went in for service their was zero wrong with engine.