Thorntons has seen total sales plummet 10.3% in its commercial division to £41.9m.
Sales also fell in its retail division to £44.9m, down 2.4% in its second quarter trading figures for the 14 weeks up to and including 10 January 2015.
Despite this, the chocolate business saw a 5% increase in like-for-like sales in the retail sector.
Thorntons warned on its sales performance on 23 December, when it said it suffered challenges with a number of grocers, as well as short-term difficulties at its centralised warehouse.
It saw a 7.8% increase in like-for-like sales during the Christmas period from 1-24 December.
The high street chocolate business said there had been high demand for boxed chocolates, seasonal specialities and advent calendars this festive season.
Jonathan Hart, chief executive, said: “Alongside very positive results from our retail division for the second year running, we were disappointed that the continued growth we anticipated in the UK commercial channel of our FMCG division had not been delivered. The challenges we experienced within specific grocers accounted for the majority of the share decline.
"Good growth in many of our grocery, convenience and high street accounts and a strong performance from our retail division gives us confidence in shopper demand for our brand and products. We continue with our transformation towards an FMCG business and the investment in our people, systems and factory is ongoing. We have good plans for the spring season and the board remains confident in its multi-channel strategy and ongoing transformation.”
Interim results for the company will be announced on Monday 2 March.