HELP!:engine went bad, Foreign Motors West are trying not to cover or help

[DIAZ]

The accelerator pedal on my 2003 x5 was broken and would get stuck when it was accelerated, making it extremely dangerous. I was coming off an exit in 3rd gear about to go into a turn , when the car wouldnt slow down, it kept accelerating. I panicked as I almost rear ended someone in the turn, braked and attemptede to downshift. I then immediately took into the dealership where i bought and service the car(FOREIGN MOTORS WEST in Natick,MA) and told them what happened. they didnt really believe me until I kept asking for a mechaninic to look at my car. When he saw the accelerator he said it was broken and needed to be replaced, they replaced the accelerator and after that the car was running rough. So I called in to Foreign motors and they told me it was a common problem with the coils on 2003's X5 3.0. The car kept running rough and a Service Engine Soon light came on, so I had to go drop off the car before my appointment as I knew something was wrong. After about 10 days the dealer called me and told me that my engine had an issue of bent valves, and that they were unsure whther this was a warranty issue or not. They told me if BMW didnt cover this, it would be about $3,000 to fix, and worst case scenerio $6,000 depending on how many valves were bent. A week later i get a call that my whole engine needs to be replaced, its all damaged and it was going to be about $12,000 to fix and that there is nothing i can do. My service advisor was literary that rude. I then asked to come in and speak to the Service Manager, his name is Lance Mitchell. He told me that this was caused due to an overrev, and this is a really rare case he only sees in his experience maybe one or two of these cases a year. He said it was clearly my fault, and then I told him that I dont ride the car hard, that this probably happened due to the accelerator getting stuck. he laughed at me and told me than in his 8 years of experience he has never heard of an accelerator misteriously getting stuck. I told him to check the record and what the mechanic said earlier as i brough the car in for this problem. He then checked his computer and was surprised. He then went on that his report said the accelerator was broken and replaced under warranty, and then i told him But you just said that in all of your 8 years of experience with BMW's you had never seen an accelerator pedal getting stuck. he then went around in circles that he had seen many accelerator pedals break off, but none that get suck. Furthermore he said that no matter how fast I was going or how powerful an engine is, the brakes would override the engine. he explained how he has track experience, and kept going around in circles. i then asked for a printout of the overrev codes, which he didnt have, and what BMW NA thought about this, and he didnt have any overrev printouts with him, or any further information, and he hadnt even contacted BMW NA. I called another dealer, herb Chambers and they told me that in the case that BMW wouldnt help me out there were other options such as finding a low mileage used engine, and they were going to work with me to please have the car sent over to them. I am just shocked that all of this is happening since I bought a BMW due to their great service and reputaion that follows their name, and Im even more shocked how bad and unwilling this Dealer, Foreign Motors West has been. Does anyone have any advice or experience dealing with BMW NA Custumer Service, as to what I should do now.

Thanks for helping out in any way
PS
the car is a 2003, with 28k miles, so its under factory warranty