Zille has apologised for referring to Eastern Cape pupils who travel to her province for better education as 'refugees'.
She has made the apology on TV, in comments to the media and on Twitter.
Her last social media reference to the issue was on Sunday night, when she confirmed that she had already apologised three times.
Zille referred to learners travelling to the Western Cape as refugees in a Twitter post last month, triggering widespread criticism.
Her statement was in reference to a protest in Grabouw over overcrowding at a local school.