Firstly, I am glad you where not seriously injured.
If this is genuine why didn’t you create an account profile with you’re name and email address ?
You can find out if this has happened before by getting pre-trial disclosure from ECP – your lawyer can tell you this and I would be surprised if they hadn’t done so already.
You will be much better served by;
Posting on specialist car forums
Contacting consumer groups, like Which ?
Contacting the AA/RAC assuming you are a member – they have dedicated legal team able to offer advice.
Contacting specialist lawyers to see if they have had other similar cases brought to their attention.
To be honest sending off the original part and doing so without having it tested first yourself is a bit naive. I assume you are after substantial damages from ECP, so there are high stakes here.
Taking them to court is going to cost you many £10,000’s
Finally this is why genuine manufacturer car parts are more expensive and a quality car like a BMW costs more in the first place.