Re: INVOICE DATE
We had a similar issue with a client a few months ago.
She wasn't able to do this online, but we were able to get the issue resolved over the phone. Not sure where you are located, but I suggest you give the AdWords billing department a call.
The link below will give you their support number. Just use the drop down to choose the country you are in. http://support.google.com/adwords/answer/1385067?hl=en
I hope this is helpful.Have a great week!
Stefan T. Martinez
-- Not an AdWords expert, just a student eager to learn more...