If you can't get in touch with your volunteer:
If you are unable to get in touch with a volunteer, consider sending them a text to arrange a time, “Hey, I wanted to give you a call to chat about your recent support with [name]. When would suit for a 15-minute chat?” If the volunteer is unresponsive, then send an email as a final option. If 6 weeks have passed it is best not to contact the volunteer.