objects - Identifying the subject: Should ‘who’ or ‘whom’ be used here?

Now, while I think I have come to terms with 'who' and 'whom', I read an article from Oxford Dictionaries that confused me: https://en.oxforddictionaries.com/usage/who-or-whom

This article states that 'the elderly woman' and 'journalists' are the subjects of these two sentences, and thus, 'who' should be used instead of 'whom':

✗ He is demanding £5,000 from the elderly woman whom has ruined his life.

✗ Mr Reynolds is highly critical of journalists, whom just use labels to describe him.

However, I believe they are actually the objects of the two sentences. If I were to replace them with pronouns, they would be in the accusative case.

'He is demanding £5,000 from her [the elderly woman].'
'Mr Reynolds is highly critical of them [journalists].'

Because the two nouns would be in the accusative case, shouldn't 'whom' actually be used instead of 'who', despite what Oxford says? I would like to know if I am missing something here.

Thanks in advance!