@Jacob, thank you very much.
So it wasn't only me who was thinking that this HAS to be implemented for the traders to start completely TRUST this system. I hope someone here listens to this cause I know alot of those Safcon techies who can suggest this to MJ are listening, otherwise, the dream of having mpesa for online transactions  becomes a dream after 2 or 3 traders are hit by this reversal thing.
./Ok3ch

On Sat, May 16, 2009 at 8:45 PM, Jacob Ayienda <jacobayienda@gmail.com> wrote:
apparently every mpesa transaction generates a unique id/code.

So all safaricom has to do is add 2 new menus (accept sent amount &
reverse) which prompts the recipient of cash to enter the transaction
code the sender receives (sender can sms this code to recipient) so as
to unlock the cash sent.

Meanwhile the cash can be held up in a virtual account (each
transaction has a unique code) such that the sender may choose to
cancel the transaction if he realises he got the wrong recipient
without calling customer care by pressing [reverse] and using the
transaction code.

Since the transaction only becomes commited when the recipient unlocks
the cash with the code sent by sender the amount remains suspended in
the virtual account till someone with the [recipient phone no. + code]
or [sender phone no. + code] can claim.

Problem solved. Feel free to poke holes in my idea. it may not be all
that perfect.