Customer Sean Needham photographed the blocked fire door at the firm's branch on Wheatley Hall Road and described it as "disgusting."
He said: "It is disgusting how they can block a fire escape off. One of my first thoughts when I saw it was Grenfell Tower.
"Basic common sense wouldn't go amiss."
Mr Needham took the photo at the branch in the Wheatley Retail Park while shopping last Thursday and contacted the store's head office to complain, but says his complaint was ignored.
He added: "I emailed the head office and received no response."
The incident comes a few weeks after London's Grenfell Tower tragedy when at least 80 people died when a huge inferno ripped through the building, trapping residents inside.
A spokesman for the firm said the rail had been left in front of the door because of the popularity of one of its clothing ranges.
They said: “Our Pep&Co range is so popular that our colleagues at the Wheatley Retail Park store left a clothes rail in front of an emergency exit momentarily whilst restocking the shop floor.
"Our colleagues work endlessly to keep up with customer demand, ensuring the shop floor is well stocked at all times but not at the expense of our shoppers’ safety so rest assured it won’t happen again”.