Citigroup Inc. has been order by the U.S. Consumer Financial Protection Bureau (CFPB) to cough up $700 million to reimburse customers overcharged by the bank through illegal credit card practices.

From 2003 to 2012, Citibank -- which is owned by Citigroup -- enrolled millions of customers in credit monitoring services and programs that promised to defer payments or forgive debt in the event of financial hardship. However, the CFPB found, when the bank signed people up to join those programs, it misrepresented fees and overstated the benefits. It also used "leading questions" and "construed ambiguous answers" during telemarketing calls.

On Tuesday, the CFPB announced 8.8 million Citi card holders were victims of "deceptive marketing" practices, which involved misrepresenting costs and fees associated with credit card add-on services, reports Reuters. Meanwhile, almost 1.8 million consumer accounts were "deceptively" charged with unnecessary same-day payment fees while collecting payments, the CFPB said.

In many cases, the bank used confusing text on credit card applications to lure consumers into signing up for extra debt-protection services even if they didn't want to pay for it, reports Time.

Many customers were also misled into thinking they were protected from fraud and identity theft, says the Bureau.

Citibank, in released a statement Tuesday, said, "Affected customers will automatically receive a statement credit or check and those no longer with Citi who are eligible will be mailed a check," reports CNN Money.

"Citi cooperated fully with the CFPB ... and has taken extensive steps to address each issue that affected customers," Citibank added.

CFPB Director Richard Cordray promised the Bureau will "continue to uncover illegal credit card add-on practices that are costing unknowing consumers millions of dollars," in a statement Tuesday.

In addition to issuing $700 million in customer refunds, Citi pay will also have to pay $35 million in fees to the CFPB's Civil Penalty Fund.