Payday lender First Financial has been fined £175,000 for sending millions of illegal spam texts.
The Information Commissioner's Office (ICO) fined the lender after 4,031 complaints were made against the messages.
The texts, which were sent from unregistered SIM cards to avoid detection, included one that read: "Hi Mate how's u? I'm still out in town, just got £850 in my account from these guys."
This was then followed by a link to the company's website.
First Financial's actions were unlawful, as people must give their consent before companies can send marketing texts.
The ICO said it was speaking with the government to get the law changed to allow it to take action sooner - a decision backed by consumer groups.
Richard Lloyd, Which executive director, said: "Consumers need the regulators to get tough to stop companies persistently bombarding us with unwanted calls.
"The government must make it easier for regulators to take enforcement action and we look forward to seeing their upcoming action plan for tackling nuisance calls and texts."
Debt charity StepChange supports the call for strengthening the regulator, after its research found 26.3 million British adults had received unsolicited calls or text messages from high-cost credit lenders, such as payday loans companies.
Of those contacted, 1.2 million adults said they were tempted to take out a loan on the back of this.
Peter Tutton, StepChange's head of policy, said: "For those in financial difficulty, the offer of a no-questions-asked payday loan can result in harmful economic choices.
"Tackling the epidemic of nuisance calls will require a broad range of measures including stronger powers for regulators, greater co-operation between regulators and measures that give consumers control back over their personal data."