They laughed at me very much versus Thank you very much

(Grammar Questions I Couldn't Answer)

A student had written "My friends laughed at me very much"  in her essay.

During the class discussion time, I highlighted this sentence.

My native speaker intuition was telling me that "very much" was wrong, and that the correct form  should be "a lot".

When pressed for an explanation, I gave the explanation that textbooks usually give--"much" and "many" are used in questions and negative statements, whereas "a lot" is used in positive statements.

But then a student raised her hand.  "But teacher," she said.  "What about 'Thank you very much' ".

So I looked this up in Practical English Usage by Michael Swan.

Michael Swan writes on page 333:

Very much  can be used in affirmative clauses as an adverb, but not usually before a noun.  Compare:
 I very much like your new hairstyle (adverb)
Thank you very much (adverb)

So why then does very much sound wrong in the sentence "My friends laughed at me very much.