Another four-day strike by First Cymru bus workers will go ahead on Wednesday, the Unite union has confirmed.
Services to and from Llantwit Major will be among those affected in an ongoing row over pay.
Locally, First Cymru says services linking Llantwit Major with Bridgend (303), Cardiff (304) and Talbot Green (321) are unlikely to run while there'll be a reduced timetable on the X2 service between Porthcawl and Cardiff via Bridgend.
Last week, Unite accused the bus operator of continuing to short change staff - with the union threatening to stage further action over the Christmas period.
General secretary Sharon Graham said: "First is guilty of trying to deny workers the back pay they are fully entitled to, in order to line its own pockets."
"Our members have roundly rejected this latest offer, which denies them pay justice and they have Unite's complete support throughout this dispute."
Doug Claringbold, First Bus' managing director in Wales said: "Throughout this extensive negotiation process, we have listened to Unite the Union member feedback and made a number of offers in order to try and settle this dispute, to ensure customers who rely on our services are not affected by strike action."
"Unfortunately, rather than work with us to find a resolution, Unite the Union has decided to press ahead with strikes, affecting our customers. Our door remains open to negotiation."
Other affected services include the 64 (Bridgend - Talbot Green) and 320 (Talbot Green - Cardiff) routes/

Former Holm View Leisure Centre could become education and community hub
ScoutsCymru members represent Wales at Royal Albert Hall Festival of Remembrance
Plans for indoor market at former Barry Wilko move forward
Police given additional powers to deal with anti-social behaviour in Barry
Senedd passes supplementary budget with £60m boost for additional learning needs
Future of planned festive events in question after criminal damage to Barry Town Hall
Consultation to open on plans for 35MW solar farm near Penarth
No Trains through the Vale of Glamorgan this Sunday
Police and Cardiff City launch operation to tackle matchday anti-social behaviour
Free leaf and fallen fruit collections return in the Vale
Barry retains Fairtrade Town status until 2029
£1m improvements planned for Pencoedtre Park as splashpad work set to begin
Plan submitted for new independent school on site of well-known charity farm
Is your hot water bottle safe?
Solicitor sentenced for defrauding Cancer Research UK
Cate is crowned champion!
WATCH: Winner of The Voice UK Cate McHugh duets with Sir Tom Jones
Barry filmmaker takes her documentary to the big screen in New York
Pupils leave their mark on new school at steel signing event
£3m refurbishment plans revealed for Cowbridge Town Hall