Do you have access to an endoscope?
If so, use it to look inside your fuel tank to see if there is any obvious contamination.
As for the diesel that is currently in your tank...
No-one is saying that you should simply dump it. Find some containers and just drain the tank, then add 20 litres of clean, fresh diesel to do your testing.
You should also be mindful that people on this forum are from all around the world. Expecting a reply instantly is a bit ambitious, given all the different time zones people live in.
I realise that you are probably frustrated, but you do need to be patient. If people can offer you advice, they will.