I used to call them on TextNow, but I've heard that doesn't work offlate. If you have a friend in Canada, see if you can reach out to them to help you with this. The wait is often excruciatingly long, see if you can use your virtual number and call them around 8am EST. I have had some luck getting through at this time.
I don't think a 5-day wait has an impact on your timeline. There are cases who missed the email and responded beyond the deadline too. Did you get any acknowledgement when you replied? Also did you change the subject line in your reply?