Money Fight Over Failed Lady Gaga Appearance

TV Service ZAO -- a media company that owns the Russian music network MUZ-TV -- filed the legal docs in Miami, claiming it paid the $1.5 mil to book Gaga for the upcoming MUZ-TV awards in June ... but the deal fell through ... and they still haven't gotten their money back.

According to the lawsuit, ZAO attempted to book Gaga through a Miami-based management firm called NWE -- which claimed it had the necessary Gaga connections to lock down the pop star for the summer appearance.

But ZAO claims NWE was just blowing smoke -- and ultimately failed to secure the singer.

ZAO claims it has repeatedly asked for its money back, but NWE has refused -- and worse ... siphoned off $300,000 from the 7-figure sum as a broker fee.