Why is it every time I go to Best Buy I get pissed off?

So I head to Best Buy after due diligence to buy a camera and some accessories. I carry along the following:

1. a 10 % coupon to apply to digital photo products
2. a printed Reward Zone certificate for $95 off
3. a printed Reward Zone certificate for $55 off

I do my business, hampered by a sales clerk with an attitude and a pimp walk (even though she was a young woman). She gets wrong what I asked for and supplies me with something much more expensive. She huffs when I tell her that it is wrong, voids everything and starts over. She proceeds to ring up the new sale, then hands me the receipt. I am expecting the following:

camera                             $xxx
accessory 1                         yy
accessory 2                         zz

Subtotal for the coupon     aaa
10% coupon           -0.1 x aaa

Subtotal                   0.9 x aaa
certificates                       -150

Tax
Total                        0.9 x aaa - 150 + taxes

I don't get that. I get a bizarre list of items, each of which displays

• an amount that is not the amount displayed on the store shelf
• a "sale" discount that brings it down to the store display price
• some of the tax for the sale
• some of the certificate discount for the sale, but not displaying any percentage or rule for calculating it

As a result, it was impossible to check the arithmetic. I am an old fart, and crusty shading to cranky besides. I check the work for major purchases. When the store displays its internal accounting nightmare to me rather than a simple receipt that can be checked, I get pissed off. Enough to get several more huffs out of the "sales" person and to get a manager over there who could explain the gobbledy-gook to me so that I could check it.

This kind of thing (but not the same thing) happens every time I go there. Last time the "sales" person could not explain why the Geek Squad would come to my house and "adjust" the TV after a couple months. It took a store manager to explain that every TV delivered from Japan comes adjusted for the store (that is, too bright and with too much contrast - so it will stand out against other maladjusted TVs). Apparently, despite the fact that maybe one TV in a thousand is used in the store as a display, IT NEVER OCCURRED to anyone that adjusting them all to store brightness and then wasting someones time traveling to houses all over central Texas is JUST PLAIN STUPID.

I am getting to be old enough that apoplexy could conceivably be life-threatening. I don't want to give up on interacting with the world, but I am pretty sick of talking to stupid snots with an attitude. I am self-aware enough to understand that I might be one, but I need some feedback to confirm or deny it.

Anyone?