Avanti West Coast should be stripped of its contract unless axed services are reinstated soon, Greater Manchester Mayor Andy Burnham said.
The Labour mayor wrote to Transport Secretary Anne-Marie Trevelyan warning the company’s existing plans for increasing its timetable will cause “two more months of chaos”.
The operator reduced its timetable from seven trains per hour to a minimum of four per hour on August 14.
This involved running just an hourly service in each direction between Manchester and London plus additional services at the busiest times.
The route had three trains per hour before the coronavirus pandemic and prior to the timetable change had two services per hour with some extra trains.
Trains were removed from the timetable in August to cut short-notice cancellations after a sharp decline in the number of drivers voluntarily working on rest days for extra pay.
Avanti West Coast’s contract from the Government to run services on the West Coast Main Line is up for renewal at the end of next week.
Last month, the company published a plan to reinstate some services on certain days from September 27.
Timetables on other days were due to be boosted “as soon as possible” ahead of another increase on December 11.
In his letter, Mr Burnham wrote: “This would mean two more months of chaos on the West Coast Main Line in the interim with resulting damage to our city-region’s economy.
“If December 11 is to be acceptable, Avanti must also commit to providing a consistent two trains per hour service between Manchester and London by the end of this month as a staging post to full restoration of the timetable.
“Unless this happens and is clearly communicated, train travel between our most important economic regions will continue to be chaotic, forcing people into their cars or into abandoning plans to travel entirely.
“Without this commitment I will be unable to support a new contract for Avanti.”
Mr Burnham told Ms Trevelyan that Avanti West Coast still has “very poor levels of reliability” with trains “regularly delayed or cancelled”.
His letter mentioned “other challenges” including tickets only being released a few days in advance, seats being double booked and broken toilets.
“These dreadful conditions would be unacceptable at any time but are particularly so now given the wholesale collapse of the timetable, something no other train company is experiencing at anything like this scale,” Mr Burnham wrote.
Avanti West Coast said in a statement: “We are already delivering on our commitment to increase the number of services we are running between Manchester and London, with three or four trains an hour departing Manchester Piccadilly at the key times of the day.
“We remain focused on providing a reliable train service for our customers and restoring a full timetable of three trains an hour all day between London and Manchester in December.
“Our revised timetable, with no reliance on overtime, is also proving more reliable – in the last week we have run 300 trains between London and Manchester with approximately one in 30 of them cancelled mainly because of short-notice sickness.
“That compares with one out of 13 trains cancelled back in mid-July.
“Nevertheless, we know that at the moment we’re not delivering the service our customers rightly expect and we apologise for the enormous frustration and inconvenience this is causing.
“We would like to thank our customers for their patience and understanding.”
A Department for Transport spokesman said: “People deserve certainty and confidence that their train will run on time, and while the change of schedule was unavoidable it should minimise the fallout for passengers.
“The problems facing Avanti are a prime example of why we need to modernise our railways so passengers benefit from reliable timetables that don’t rely on the goodwill of drivers volunteering to work overtime in the first place.
“Government will consider all options when Avanti West Coast’s contract expires on October 16.”