How can I help with this please?
Surely if there is a new owner then it isn't your car?
Was this vehicle seized for no insurance?
It would not normally be seized for log book issues.
Ok. So the issue is no insurance then.
They are entitled to seize and crush the vehicle if a person is found driving without insurance.
They used to do that all the time.
they have relented now and clearly are offering to return it to you if you can prove ownership.
The reality though is that they are demanding the original owner confirms your ownership which is not unreasonable given that the transfer is not complete.
Unless you can get them to do so, they may well refuse to relent. They don't have to release in either circumstance so it is a matter of negotiating with them.
You can also approach the old owner. There may be liability on their part as they didn't do the transfer expeditiously so they may be keen to avoid that.
Can I clarify anything for you?
No, they can remove vehicles found to be used by uninsured drivers and dispose of them immediately.
They do not generally do that now but they can.
All the best.