Yes the email doesn't seem to serve any purpose other than to say 'we know what you've done' and try to make people feel guilty.
It's the detail that they've gone into that I find odd - 'clearly we've made a mistake as the calendar costs £39 and contains 12 pairs of socks and did not have the 2 for £10 badge ....'
I usually pay around £10 for 5 pairs of socks on Amazon and they are cotton and wool mix.
WS socks are cotton and polyester, so it's not completely outrageous that someone might think that 12 pairs were included in the promotion