Royal Mail strikes are forcing retailers to urge consumers into their shops rather than risking a delivery not arriving ahead of Christmas.
The British Independent Retailers Association said spending in-store would provide “certainty” this Christmas.
"If people want to be certain of getting deliveries in time for Christmas, they need to go into stores," said Waterstones chief executive James Daunt.
Daunt notes that for a large retailer such as Waterstones, getting customers through the door shouldn’t be a problem.
However, smaller, independent firms that rely on national deliveries will be negatively impacted.
"I know it's easy for us to say go into shops, as we're a national retailer," Daunt told Yahoo news.
"It's the independent retailers all over the country who will be suffering the most from this. I feel desperately sorry for them.
"For national retailers, it's more swings and roundabouts. What we lose online, we make in stores."
Employees at Royal Mail, owned by International Distribution Services, started their Christmas strikes last week.
Services were disrupted on 9, 11, 14 and 15 December, with two further strike dates, 23 and 24 December planned, with 115,000 staff walking out.
The strikes are likely to cause chaos around Christmas with deliveries.
Competitors, such as Evri and DPD, have already seen demand for their services shoot up, causing a swathe of complaints about slow or non-existent deliveries.