Sorry but that's plainly not true. If they put the original price up 12% and then discounted the resultant price by 12% you still received a discount on the original price. That's just basic maths.
So let's stand in the middle of a darkened road in dark clothes and see if we can also get hit by a moving vehicle.
Police showing their total lack of critical thinking.
I've lived here many years and regularly post letters abroad.
I have never been asked for any ID whatsoever nor have I seen
or heard of anyone else being asked to show ID for this.
I think you may be confusing this with parcels being posted.
Was there some reason why you didn't ask immigration about the 65k/month
method which you say was acceptable at your previous immigration office.
If not, maybe you should go back and ask and save yourself all the worry