"What next? Seriously, why is voting any different from these other very important uses of computers? Doesn't it make more sense to fix the problem rather than ban the machines?"
There's a very good reason why it's different: because in a secret ballot recorded by computer there is no way to verify the integrity of the data. In all of the examples you list above (electronic trading, ATMs), it is possible to compare the data in the computer with the data you expect to be in the computer.
For example, if you take €200 out of an ATM and your bank balance is debited by €500, this error will be pretty obvious to you. If you cast a vote in an electronic election, you can never know if your vote was recorded correctly.
There is no way to get around this problem without a voter-verifiable audit trail (VVAT).
In any case, the election in question is in 3 weeks' time, which doesn't really allow adequate time to fix the machines, even if that were possible.