no - a loan is not a savings account - theres 2 totally different phillosphies there
savings works on the basis of debit - that is, your money has to be there to use it and it is 100% "your" money
loans works on the basis of credit - that means you have a negative balance that you have to pay back to zero and its not "your" money
i wouldnt be surprised if econet roll that out in future though, seeing as they own a bank now - but i'd be very wary of quick instant loans without security - they usually attract extortionately high interest rates as can be seen in the UK right now with the likes of wonga.com