Boohoo and River Island, two of the biggest fast-fashion retailers in the UK, are apparently addressing quality issues with suppliers, which could result in payment delays or threats to return merchandise.

The Times reports that River Island is the most recent store to voice concerns about product quality with its suppliers. The fashion shop is believed to have asked for price reductions on products that it said did not live up to its standards.

One supplier told the media outlet that River Island had threatened to return the entire order unless a discount was offered after it was accused of sending a shipment of clothes that were judged to be “slightly too short in length.” Another supplier said the retailer’s demands for discounts had “gone into overdrive.”

“They’ve become very hot on open costings,” one source said. “If we give them a price for a product, they want to know how we’re breaking it down and if we’re costing in that 100 percent.”

A similar incident had previously occurred at Boohoo, which had reportedly been delaying payments to suppliers it believed were making defective products.

The decision to withhold payments, according to a source for the outlet, was made as part of a campaign to “improve quality following a marked increase in faulty goods being delivered.”

According to the source, the business had the legal right to withhold payment until the problems were fixed in this instance.