I do a fair bit of internet shopping, and there was a time when I prefered my parcels to be delivered by the postman - not anymore!
Take the last parcel I ordered. On monday, I was home all day, had some friends over for lunch, so we were sitting in the kitchen, close enough to the front door that I would definately hear if someone knocked on it. In the morning I'd checked the postbox (it's on our front path, next to the road), and after my friends had left I checked again. There were a couple of letters and a slip to say they'd tried to deliver a parcel!
Now parcels don't come with the normal postman - they come seperately, usually by van, but this was a small parcel so it could've been the normal postman who had it on his scouter. But he definately didn't knock on the door!
In the past we have suspected that they haven't tried to deliver parcels, and just send out the slip with the ordinary post (on one occaision the slip turned up three days after they say they've tried to deliver), so we complained. My husband sent a very polite e-mail outlining the problem as we saw it.
Today we got the reply. They say they've talked to the postman concerned, who now recons it was tuesday he tried to deliver the parcel, but had mistakenly written the wrong date on the slip! Strange that the slip turned up the day before he says he tried to deliver, and if they looked at the date and time that our complaint was sent then this explanation would have been illogical. it would mean that we'd complained before we'd checked the post box!!!
So at some point this evening when the steam has stopped coming out the top of my head, I'll be replying to their e-mail in no uncertain terms!

