Well, actually the 5 per transaction limit was created after a large enough number of elderly people got scammed by the various fake email/phone call scams telling them to pay ATO (or similar) outstanding amount immediately or face a X00% penalty.
Subsequently their relatives would find out and try and get Coles to refund the purchased MCs or Vs.
So, to try and stop this fraud/scam - they instituted the 5 per transaction automatic limit which cannot be over-rode by a supervisor.
Annoying that the various Coles group divisions are not up to speed on it and keep offering "limit 10 per transaction".
True it is an inconvenience to those of us who are seeking to max the points party - but personally, if it stops some elderly person being ripped off then I do not mind having to do 2x the transactions.
Just saying...