NB. DNS changing software simply changes the DNS that your machine uses from the default (your ISP usually) to their own DNS. You then go to what you think is barclays, but it's actually the bank of Mojumbo, Nigeria: Or whatever.
The simple fact is though that if you don't click anything dodgy on the net; have proper firewall and antivirus updated regularly: This won't get you. I imagine those affected have either been naughty boys or it's a family computer and someone else in the house has?
The main thing is a GOOD antivirus will catch these issues even if your machine is compromised - although it may take a day or two to catch up with the latest malware unfortunately. It's important that your signatures automatically update and that you enable smart protection or scan weekly.
Lastly; any damage done by a 0-day malware release that's hit your machine may not be undone by the antivirus software. If your software flags up an issue: It will remove the problem but can't be aware of what has been changed. Bringing it back to this example then; If software has changed your DNS settings then you might remove the software but it won't resolve your DNS. You need to be aware of the impact any detected malware may have had. A bit of googling isn't a bad idea.
And of course; if you are running Windows 7 64-bit with the standard UAC settings: Then the issue mentioned above cannot happen; ipconfig is a secured piece of configuration that only an administrator can change.
This is a subject that could run and run obviously. Bringing it back on topic it's good that the bank are refunding the money... It shows that their aware that this is a serious problem and it certainly sounds very sophisticated. I guess the lesson is that any changes to their security policy will be sent to you in writing or be shown in the first page flash screen.. So if something has changed unexpectantly: Give them a call.