Bobby Browns lawyers are suing the singer for $90,000 (£45,000) over claims that he owes them in unpaid fees.The firm filed papers at Los Angeles Superior Court on 15 August, alleging Brown racked up the five-figure sum using its "professional services" while divorcing singer Whitney Houston in 2007.The former couple made its split permanent last year, fifteen years after marrying.Brown's representatives have yet to respond to the lawsuit.