Company bosses should be held personally responsible for nuisance calls, consumer group Which? has urged.
The group said just four of the 22 fines issued against firms for nuisance calls since April 2015 had been paid in full and suggested that some bosses were closing their businesses only to open new ones as a way of escaping penalties.
Changing the law so that individual directors could be held to account would help bring "rogues" to justice, Which? said.
Alex Neill, director of campaigns and policy at Which?, said: "Millions of people are still being pestered by nuisance calls and it's time for tougher action that holds responsible company directors personally accountable for the unlawful actions of their companies.
"This will stop rogues stepping around the rules by closing one business and re-establishing a new one, and avoiding fines for making nuisance calls."
Under the existing laws, just four of the 22 fines levied against firms since April 2015 had been paid in full, with two part-paid, Which? said.
The group said in the remaining cases the fines had not been paid at all or the firms had gone into liquidation.
Research carried out for Which? in May found that 81% of Britons had received at least one nuisance call that month, with 40% of those saying they felt intimidated.
The survey of 2,003 people, carried out by Research Now online between May 20 and 26, found that 79% agreed senior directors should be held to account if their firms are engaging in nuisance calling.