Getting a refund & getting a VDH license for Firefox are 2 independent activities. You have asked Jérôme for a refund of your license for VDH for Chrome & he will take care of that in due course.
Meanwhile, there is a VDH license for Firefox that you can buy separately. Your license for Chrome does not get, to use your term, converted. You can buy the Firefox license now, or you can wait for the refund money to show up on your credit card before you buy the Firefox license. That's up to you. The 2 licenses have different features, therefore different prices. Some people here have one of each. The licenses are not connected in any way, just as Chrome & Firefox are not connected in any way.