The move follows its £19m acquisition this summer of Loanmakers.
DebtMatters, which was floated on the London Stock Exchange in June 2005, has prospered through the growth in popularity of the Individual Voluntary Arrangements scheme, set up in 1986 as an alternative to bankruptcy.
The use of IVAs has increased in recent years as UK debt has soared, with 12,228 issued in the third quarter of this year - a 118 per cent year-on-year rise.
Biss Lancaster's Manchester office won the brief after a pitch, understood to have been against Tangerine and Citypress.