嚷 can mean shouting loudly or complaining/fussing repeatedly. 嚷嚷 (rāngrāng) is the reduplicated form meaning 'to make a racket' and is more colloquial.
mistakes
Note the tone difference: 嚷 (rǎng, 3rd tone) when used alone, but 嚷嚷 (rāngrāng, 1st tone) when reduplicated.