I have asked Toolstation to let me open boxes at the counter and they have been fine with that. I also insist on doing so at Screwfix now. Example: You order 3 6A RCBOs, 2 16A and 2 32A...when you get home or to the job, some of the boxes, although labelled correctly, contain the wrong ones. presumably returns that have been bunged in any old box and not checked at the return stage and simply put back on the shelf. Anything I get at Screwfix gets checked immediately because I had so many missing bits previously. Boxes/packaging which has obviously been opened before usually means missing parts from screws/bolts etc to vital components that you can't buy separately. If the counter is very busy, I just go to my vehicle and check everything there and go straight back into the store if anything is amiss.
The good news is that there are many online stores that stock every kind of bolt/machine screw/nut/fastener that you could imagine...and many you have never heard of...I love browsing these places (sad old git that I am) and sometimes you hit the jackpot for a job you have on or might encounter sometime. That's why I have a dozen FatMax organisers full of "stuff"! My local Homebase closed a couple of years ago, and they were selling stock off ridiculously cheaply...I mean so cheap it was a give-away. Now, I didn't actually need the security bolts with the torx security head, the one with the pin in the middle, but I bought all the stock they had, in every size, and they were s/s so my magpie brain just couldn't resist. OK, maybe 200 all in, in different sizes, most too short or too long, however...I used one (cut down) to fix my neighbour's electric golf trolley for which he had been quoted £140 to repair, and another one to fix his grandson's bike saddle. So, I have 198 left, but those 2 repairs netted me a litre of Tanqueray gin and a nice bottle of Rioja, both worth more than what I paid for all the fasteners, so I'm happy with that.
(Just read that back...really, I need to get out more and get a life!)
PS: I actually miss my local Homebase because you could sometimes find just what you needed for a weekend DIY fix 5 minutes from my house. Another plus is that when they closed down they contacted my local branch of the Men's Shed charity for which I do most stuff nowadays and gave us all their "staff tools". These were tools like screwdrivers and hammers and pliers etc that they used to build and maintain the shelving and displays. Apparently, when units needed changing/installing the staff just took the tools they needed from the displays and once used they got put in huge bins...thay gave us those bins full of stuff, with the barcode labels still on them and used once. Sorry, I'm rambling, but I would add that Timco gave us a huge batch of display stands and hundreds of bolts/hinges of EVERY sort/handles/castors...some really beautiful brassware items...these things allow the Shed to do repairs for local people without charge, so that was a very valuable contribution to the Shed.
Finally...if you do buy from Screwfix, do you "top-up" your bill to the nearest pound to donate the extra pennies to the Screwfix Foundation? Personally, I do, but always assumed I would never actually see a return.
At my local Men's Shed we needed some specialised interior doors to separate the workshops. We applied to Screwfix for a contribution ( I can't reveal the exact amount) to assist us in this endeavour. They asked us to submit the invoice for the works and shortly after sent us a cheque for the few thousand to cover the whole cost!