New York City is suing T-Mobile for what it calls “abusive sales tactics” at Metro by T-Mobile stores, the wireless carrier’s prepaid phone brand.

The city’s lawsuit says dozens of stores sold used phones to customers as new, charged fake taxes and unexpected fees and offered financing for phones that resulted in higher-than-expected prices. The city also says a 30-day return policy is deceptive and comes with restrictions.

The city filed its lawsuit in a New York state court on Wednesday. New York’s attorney general is separately leading a coalition of states in suing to block T-Mobile’s $26.5 billion deal for rival carrier Sprint.

T-Mobile says it’s investigating, as the allegations are “at odds with the integrity of our team.”

(AP)