Despite new limits on debit card interchange fees, the price of Slurpees has stubbornly remained the same, according to a survey completed by the payments industry's lobbying group.

The Electronic Payments Coalition released data on Thursday finding that some merchants have not lowered their prices since Oct. 1, when federal caps on debit interchange fees went into effect.

Those findings were unsurprising given their source. The EPC, which represents financial institutions, vehemently opposed the interchange fee caps that were required by the so-called Durbin amendment to the Dodd-Frank law. The lobbying group still argues that the amendment is "harmful" to consumers.

Retailers backed the swipe fee caps, and some said that interchange regulation would result in lower prices for consumers. But the EPC said its research has not found evidence of that.

The payments group says that 16 out of the 21 retailers it visited this fall either raised prices or kept them the same since Oct. 1, and that on average customers paid 1.7% more for goods in that time.

The EPC collected the data during 84 shopping trips at 21 stores across the country. Its representatives bought the same items during four different trips to each store, before and after the Oct. 1 fee-cap implementation date.

The group highlighted its findings at 7-Eleven Inc. and other vocal supporters of interchange fee regulation. The price of Slurpees remained a consistent $1.49 from September to November, according to the EPC.

The group also found that prices for items at a Wal-Mart in Boston increased by $1.07, or 3%, during that period, and that prices at a Walgreens in Little Rock, Ark., rose 73 cents, or 2.9%.