You have it in writing. Print them off (just in case they are deleted or lost in error) and contact Trading Standards.
Which "authorities" are you supposed to be contacting?
The responsibility is that of e-Buyer, not you, to take it up with the couriers - this ceases with e-Buyer when you have received the goods in full and undamaged.
Again the fact that e-Buyer's new systems are giving staff "the wrong information" is not your responsibility.