Rail disruption is set to continue in Wales on Monday 22 August after the announcement that there will be no direct trains linking the north and south of the country.
This is because "staff shortages" mean the signal box at Hereford cannot be operated.
The Network Rail signal box is around a third of the way along the Transport for Wales (TfW) Cardiff to Holyhead service.
From 6pm Sunday evening to 6pm Monday replacement bus services will run between Shrewsbury and Newport.
A TfW spokesperson said an agreement with other train operators had been reached and tickets would be accepted on other routes, such as via Crewe and Birmingham.
Passengers on Monday are being urged to check their journey before they travel.
It comes after train strikes affected services on Thursday 19 and Saturday 20 August.
Two unions, the National Union of Rail, Maritime, and Transport Workers (RMT) and the TSSA, took part in the industrial action.
Just 10% of services were scheduled to run across the weekend in Wales as a result.