Passed an ad in the MTR station today that says something like 40% discount if you take the MTR from selected stations; there were quite a few of them. Didn't find any info on their website.

The 50% offer in combination with a taxi is still valid, until end of June but only applies to Kowloon and Tsing Yi station: MTR > What's New

Seems they are quite desperate to fill the trains ...