Bosses at trentbarton say the driver shortage crisis is partly to blame because some drivers have left to become lorry drivers.
The bus company has blamed a country-wide shortage which with services having been affected services across the county.
Services continue to be disrupted for the fifth successive day.
Union leaders have said that the shortage of bus drivers in the UK is being caused by better pay being offered to drive lorries.
The supply chain struggles have seen prospective long-haul drivers enticed by wages of more than £50k a year, it's been claimed.
Officials at trentbarton have said that the issue is part of the problem - but that a small percentage of its drivers have left this year to drive lorries.
But the bus company said that it has had more applications to join its driving teams so far this year than in the whole of the last 12 months.
A trentbarton spokesman said: “The HGV issue is part of the problem, but less than two percent of trentbarton’s drivers have left this year to drive HGVs.
“Some drivers have decided to retire, in some cases after being on furlough during the pandemic.
“There has always been turnover in drivers but the delays in obtaining provisional licences from DVLA for new drivers has meant the number of new drivers has not been able to keep pace.
“trentbarton has had more applications to join its driving team so far in 2021 than in the whole of last year. So the problem will be resolved as quickly as they can get new drivers trained and qualified.”
On Monday morning, October 25, trentbarton Tweeted that the company was "between a rock and a hard place" due to the disruption.
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