The news comes after the town's MP Daniel Kawczynski and council officials held crunch talks with the contractors Casey last week, and it was revealed that the work will not be finished by its November deadline.
A programme of work to lay York stone and granite setts, install new street furniture and improve lighting on Pride Hill was due to end on November 9.
But now the work is set to pause mid-November and be suspended for Christmas before re-commencing next year.
The BID met with council officials on Wednesday to express concern about the work.
Seb Slater, executive director of Shrewsbury BID, which represents more than 500 businesses in the town, said: “It is totally unacceptable that businesses and the public continue to be negatively impacted by these works in this way and we have met with council officials today to express our concern.
"We are calling for decisive action to be taken by the council to ensure that the whole town is fully accessible to the public before the Christmas trading period, and to guarantee that future works are managed in an appropriate way.
"It is absolutely vital that during improvement works businesses can continue to operate normally and that footfall and trade for their businesses are not adversely affected.”
The work forms part of the £12 million Shrewsbury Integrated Transport Package (SITP) which has seen other projects carried out, including at the English Bridge gyratory, Meole Brace roundabout and Reabrook.
Another part of the SITP programme gets underway in Shrewsbury later this month. Murivance and Town Walls will be closed for resurfacing from October 29 for approximately one week.