Placeholder change

In CREDIT card form, it says MM/YY as placeholder but when you type it accepts MM/YYYY only, that creates a wrong impression on users and many orders are failed now.

– How do we CHANGE the placeholder to correct it. Unfortunately all coming via IFRAME so couldn’t see an easy way. Any help?
– I checked in their API, they do have one parameter but no such URL to append just like in their documentation.