"Awfully" or "awful"?

I believe that the person who suggested you should use 'awful bad' has an awfully bad command of English and it would be an awful idea to abandon the correct use of 'awfully' as in your exemplary sentence:

Your snoring is awfully bad.

Just in case we’re still pursuing this, the OED’s earliest citation for the use of awful as an adverb is dated 1818. There are subsequent citations from Mark Twain and Anthony Trollope.

Merriam-Webster's Dictionary of English Usage on awful vs awfully.

"The intensive adverb awfully was attacked as a Britishicism by Richard Grant White in 1870. The Oxford American Dictionary as recently as 1980 continues the depreciation of the intensive with the remarkable claim that "careful writers" avoid it. Perhaps so, but good writers have certainly not avoided it since it became established in the mid-19th century. Some of our examples are from fiction and drama, but others are from ordinary discursive prose"

They give 14 examples of awfully as an intensive adverb, from writers like Wilde, Kipling, James, Huxley, Maugham.

What is "awful/awfully" doing here? It is modifying the adjective "bad" (telling how bad).

Which part of speech can modify an adjective? Adverbs (Adverbs modify verbs, adjectives, other adverbs.)

Which word is the adverb? "Awfully."