I am unable to book the slot. I have been trying to book it since I received an invitation but it says “ Times slots are available on a first come first serve basis. At this time all time slots have been selected. Should more times slots become available you will receive an invitation to reselect.”

I am unable to book the slot. I have been trying to book it since I received an invitation but it says “ Times slots are available on a first come first serve basis. At this time all time slots have been selected. Should more times slots become available you will receive an invitation to reselect.”