Back on topic: To the OP.

So what you are saying is that they made a mistake, and they realize it so they gave you twice the amount credited to your account as a apology.  But you want even more from them?

They know they messed up the 0.05, and they made it up to you with a gift voucher of 0.1.  You can't withdraw a gift voucher!  That's like you going into a Best Buy after buying a service of theirs for $10 that turns out to not function.  They realize it was their mistake, and the manager offers you a $20 gift card and you take it.  Then you go right back up to the manager and demand your $10 back!  The $20 in this case represents full compensation for your loss.  You can't have your cake an eat it too!  If you wanted your original 0.05 back, you would have told them that and told them you wouldn't accept the 0.1 as compensation (not sure why you would do that, but it would be your prerogative).  I bet you are just confusing them right now since they gave you a gift voucher to apologize for their mistake, and you accepted it and are now saying you didn't get your money back!

Think of it this way.  You deposited 0.05.  They f**ked up and didn't credit your account.  They apologized, and not only gave your your 0.05 credit to your account, but added another 0.05 to "try and make the customer happy."  Why not just use it for what you originally intended to and move on?