A number of trains have been cancelled or delayed this morning due to a shortage of staff.
Passengers say Great Western Railway trains heading to Wales have been cancelled up to four times already.
It comes after a new timetable was launched today offering commuters more train services and also faster journey.
One commuter, wrote on Twitter: "Four trains cancelled between Swansea and Paddington today. 'Shortage of train crew', bloody disgrace."
GWR have issued information on their website detailing the delays customers are experiencing today.
It states: "An amended timetable is in place affecting some journeys between London and Penzance, London and Swansea, and on some other GWR routes. Where trains are able to run they are expected to be very busy.
"Those with tickets for travel on Sunday 15 December will be allowed to travel on Monday 16 December when GWR will be operating its full timetable.
"Ticket restrictions have also been lifted and customers can travel on earlier services."
"The usual compensation arrangements are in place should customers be delayed, and customers who choose not to travel will be entitled to a refund. GWR is offering to waive the administration fee for those who choose not to travel."
There was also problems in mid Wales when a broken down train blocked the line between Newtown, Powys and Shrewsbury. Officials said they expected disruption to last until around 2.30pm. Shuttle buses have been organised between Newtown, Welshpool and Shrewsbury in both directions.
There will be a reduced service between London Paddington and Wales.
Yesterday, , for the same reason. More than 180 extra train services in Wales will be provided from today.
A TfW spokesman said: “We are continuing to do everything possible to ensure the maximum number of services are operating every day and this time of year can always be challenging, particularly on weekends, and we’re sorry that there have been a number of cancellations on our network today.
