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/

Police find evidence of a large-scale cannabis cultivation at Riverside Place property fire
Network Rail confirm closure of Brookside level crossing in Dinas Powys
Police given powers to ask people to leave Comeston Lakes Country Park
Only remaining Post Office in Dinas Powys could close this October
Planned children’s role play centre could be given the go-ahead by Vale Council
Marie Curie Garden Fayre deemed huge success
Council seeks views on Future of Colcot Sports Centre and Buttrills Playing Fields
First Minister quizzed on further devolution, budget decisions, and misinformation in FMQs
Extreme heat leads to changes to services and closures
Severe Heat Warning Set to Disrupt Rail Travel Across South Wales This Week
Communities asked to support older people across Wales during severe heat warning
Caribbean Community Wales Brings Wales‑Wide Launch to Barry This Weekend
Community Award winner calls for sanitary bins in men’s toilets after living with prostate‑cancer‑related incontinence
Cardiff Airport Backs Holiday Safety Campaign Honouring Rhoose Teenager Tom Channon
Barry Dock RNLI and lifeguards helps welcome King’s Baton Relay into Wales
Vale Food Trail draws more than 1,500 visitors during two‑week celebration
A former aircraft hangar is set to start building electric cars
Councillors grill Welsh Water and Natural Resources Wales over state of local bathing waters
Wales’ new local government and housing minister faces questions in the Senedd
St Nicholas Primary School Earns UNICEF Gold Award for Children’s Rights Work