Wheelchair users "cannot get round" many WHSmith stores because the aisles are crammed with extra baskets, peers have heard.
Baroness Sal Brinton said she no longer wanted to visit the retailer because it is difficult to navigate in a wheelchair, despite most of its shops having good access.
The Liberal Democrat president told the Lords: "You can get into most WHSmith shops if you're in a wheelchair, but unfortunately they have a new policy of cramming extra bits in the aisles - you know, the sort of hanging baskets that you can pick your crisps from.
"And that now means that in many WHSmiths, especially in tight places like stations, if you're in a wheelchair you cannot get round the store.
"So it may be accessible to get in and the ramp may resolve the problem, but it actually doesn't make you want to visit it any more at all."
She also criticised the County Marriott hotel in central London for not having access fit for a five star hotel, despite having made adjustments recently.
Baroness Brinton said she asked the hotel what had changed: "They said that you still have to go round the corner to the back, up in a scissor lift, doors have to be unlocked, you no longer have to go through the SeaLife centre, you can now go straight through into the back of the hotel - my Lords that is not good enough for a five star hotel."
She praised the Institute of Civil Engineers for having a "wonderful example of how you can deal with a listed building and accessibility", but said the Institute of Mechanical Engineers nearby had not done the same, saying: "The last time I went in I had to enter via an outside stair lift through somebody else's conference room to get to the event I wanted to travel to."
Baroness Brinton made the comments as peers debated Conservative Lord Blencathra's Equality Act 2010 (Amendment) (Disabled Access) Bill at second reading.
He said the Bill aimed to get equality for wheelchair users, by legislating that if a building has a step of six or 12 inches, a ramp suitable for wheelchairs has to be provided.
The requirement to remove the step of six inches would come into effectively immediately if the Bill is passed, while the 12 inch rules would come into effect a year later.
Lord Blencathra said: "This time we are not just going to go away and shop elsewhere: passing my Bill or something like it will not undermine the principle of reasonable adjustments in the 2010 Act, but would grant 800,000 wheelchair users access to about 60,000 of those 71,000 shops currently inaccessible."
Conservative peer Lord Holmes of Richmond, speaking in support of the Bill, said: "On Black Friday, no matter how bad the bustle and crush is, how blacker today is for those of us wheelchair users and other access impaired who can't even access the stores to get to those bargains."
Shadow equalities spokeswoman Baroness Gale said Labour would support the Bill, which was widely backed by peers in the debate.
Home Office minister Baroness Williams of Trafford said: "The Government believes that the existing legislation is already comprehensive in this regard.
"We do have every sympathy for the aims of (Lord Blencathra's) Bill but there are a couple of areas that I'm concerned about."
She said the Bill would remove the "reasonableness filter and require service providers without exception to provide ramps for wheelchair users wherever there is a single step that is less than six inches in height in a public area".
Lady Williams also said the Bill would take "no account of the cost of the installation".
The Bill passed second reading and will undergo further scrutiny at a later date, but will struggle to clear all the parliamentary hurdles without Government support.