The problem here that I and many other people experienced was that we are using a DEBIT card and as such when you transact and enter a pin, you expect the money to go out directly.
I transacted on the 16th of December at two stores - cash back at a checkers and payment at a jewelry store...both debit transactions on my global one card and pin authorised. I received the sms's that money was taken out. All good.
Yesterday morning received two sms's that those exact amounts were taken off again.
Go to bank and it checked my statements - on the 16th no money actually left my account, yet I received those sms's stating money left.
Now for me it was not a big deal...but for other people it was. The main gripe here is the fact that it's a damn DEBIT card meaning immediate payment...no money in account...no pay etc.
EDIT: As for the apparent double billing - per your sms's it will definitely look like your are doule billed. On the statement you will see no money left on the date of the original transaction.
Not saying that there weren't genuine case of double billing, but most often than not people just used the sms's as proof and not the physical statements - was the case for 20 odd people at the bank yesterday morning with me.