Good heavens, I thought riffing was a spontaneous solo on a musical instrument!

Couldn't find any other mention of retrenching, but I did find something fascinating:
The most noticeable difference in pronunciation is probably the flat "i", so that "six" is pronounced in a way sounding like "sucks", and "today" like "to die". This is a part of the vowel shift that has occurred in South Africa as well as New Zealand. Below, the latter word is how the former word sounds to the ears of a non-South African: Rewrite in IPA
pan --> pen
pen --> pin
pin --> pun
pun --> pan One difference between (white) South African English and New Zealand English is in the pronunication of 'ar' and 'ow', as in the pronunciation of the sentence 'park the car downtown'.
New Zealand: pahk the kah dehwn tehwn
South Africa: pawk the kaw dahwn tahwn


From
http://www.nationmaster.com/encyclopedia/South-African-English