This is not a rant about companies keeping information on me. Though the amount Tesco think they know about me is quite frightening. This is more about why companies don't use their databases properly.
I've twice had the experience lately of phoning different companies and going through the automated voice thing. Part of the routine is that you have to key in your customer number. So far so good (though very annoying when, after you've done all that, they cut you off picking up the phone and you have to go through the whole routine again). But then I had to give the whole damn' number to the person I was talking to. "Is it not there on your screen?" "No." "Why did I just have to key it all in then?" "Don't know where it goes. But we don't get it." So one bit of the database is not talking to another bit of the database.
And then I recently got one of these coupon things at Tesco for a certain brand of goods. I checked for this item regularly till the coupon ran out of date and then, being in a picky frame of mind, I went to the customer services desk and complained. And they said, "We don't stock that, we never have." The coupons are apparently taken off Tesco's national database of goods without referring to whether or not they're stocked in any particular store. Given that most people most of the time shop in the same store, could the coupon machine not interrogate the store's inventory to see if it was worth giving me that coupon? Of course it could. But it doesn't Missed a trick there, Tesco.