Just effectively they have monopolised, have unfair trading practices with small businesses that supply goods, are increasingly changing product for their own brand which then means the "lowest price guaranteed" is pretty null and void because you can't buy their items anywhere else.
Just noting, I watched this a long time ago, but it left a bad enough taste in my mouth to stop me from going there any more
I now just go to the specialist stores. Some times might be a bit more money, but often much better service.
Sure, strictly speaking it's not as convenient.. but good service, good quality (variable) , not supporting a Monopoly.