Online appointments fully booked constantly

I have been trying for 4 weeks now to get an appointment for my kids eye tests. This will be their 3rd year. Every time i log in the system shows fully booked. I thought if i wait until midnight and immediately log in when the new day for the 8 week window becomes available i will get a slot. Lo and behold at 2 mins past midnight it is already fully booked. How is that even possible and you cant make appointments any other way except online. This just rediculous at this point. We are a family where both my husband and I are unemployed and both my kids need glasses. But we cant even get an appointment.