The group behind strike-hit Southern Railway has warned over fresh disruption for long-suffering passengers ahead of next week's planned union action.
Go-Ahead, which runs Southern through its Govia Thameslink Railway (GTR) business, said while the service has "stabilised" in recent months, the train driver overtime ban set to start on June 29 would cause more "unnecessary disruption" for customers.
Its warning came as the group revealed that passenger revenues for the year to July 1 are expected to drop by around 4% on its GTR service, with passenger journeys also down 4%.
The group said: "There has been no significant industrial action on Southern services in the last five months and, consequently, service and performance levels have stabilised, allowing the company to deliver more reliable rail services to customers.
"Disappointingly, the Aslef union has called for an overtime ban for Southern train drivers which, if it goes ahead, will result in unnecessary disruption for customers."
Go-Ahead said it "remains fully committed to resolving these issues to provide improved services for customers and reduce uncertainty for our stakeholders".
The firm alerted over profits in February after a year of crippling industrial action, revealing full-year rail profits could be impacted by up to £15 million amid ongoing uncertainty over union relations.
The group said in its latest update that it remained in talks with the Department for Transport over potential penalties for breaching its contractual obligations but said the outlook for rail profits remains the same.
Southern has been involved in a bitter dispute with unions over proposals for so-called driver-only operated trains, with conductors holding several strikes in the past year, while drivers have separately walked out due to the row.
Go-Ahead also revealed in its update that passenger growth has continued to slow for the Southeastern line, with passenger journeys expected to be down 0.5% in the year to July 1.
The Southeastern line has been put out to tender, with Govia - Go-Ahead's joint venture with French firm Keolis - among those firms so far on the bidding list.
Despite the fall in passenger journeys, Southeastern passenger revenues have risen by around 3% on the service.
Go-Ahead said full-year revenues were around 4.5% higher for its London Midland service.
Bus revenues are expected to be around 1% higher, with passenger journeys flat, partly as a result of some routes being cut to "match passenger demand and reduce costs", according to Go-Ahead.