Like wraps said sharpie (if you can get away with it) or cut new ones or just let it slide. Anyone who won't understand what those numbers mean without the extra dot..... is just stupid.
I have a file that was approved and I printed it.
I now see the times like this
9.30am - 4.30pm - note one dot?
I have never seen a time posted like that and wonder...is this acceptable?
I knew a person that used a period for times and phone numbers as his "style". Most customers didn't even question it.
obviously a case of colon trouble