Check out these vendors on the Language Resource Online website to see if they have specialized Assamese language learning courses:

Transparent I Can Speak Assamese

Transparent Assamese Now!

Transparent 101 Languages of the World Assamese

Transparent 31 Languages of the World Assamese

Auralog Assamese Beginner V5

Auralog Assamese Intermediate V5

Auralog Assamese Advanced V5

Auralog Assamese Complete V6

Eurotalk Talk Now! Assamese

Eurotalk World Talk Assamese

Eurotalk Vocabulary Builder Assamese

Topics 33 Language Instant Immersion Assamese

Topics 18 Languages Instant Immersion Assamese

Topics Assamese Instant Immersion

Topics Assamese Audio Instant Immersion

Topics Assamese Audio Advanced Instant Immersion

Topics Assamese 1.5 Instant Immersion

Topics Assamese Pro Instant Immersion

Rosetta Stone Assamese Level 1 Personal Edition

Rosetta Stone Assamese Level 2 Personal Edition