Thank goodness you have found the UKPT. Your experiences are so like what others have gone through, so take some heart that you are not unique or odd. Please look a the drug test page of our website here:
If you calmly and firmly insist on your rights, you can win through.
We can provide professional advice/letters which can be useful when dealing with a solicitor or other agency.
Do read our site and brief yourself to be able to respond to those who do not understand by explaining that the body's subconscious reaction to a threat is to "turn off the tap", and that the conscious cannot overide that.
Keep in touch, or email me at the support address at top of page
In fact if you email me your address, I can post you our glossy brochure to be shown to whoever needs to see it.