@Dave *****
that I understand...and the Thai Immigration office does too.
Obviously they are swamped and spacing out the work. They wrote time and date for you to appear. Do it.
But as you are worried...
Suggest you go back again and ask one more time....and take a Thai friend along with you if you can.
At this time...there is nothing more anyone can do or say... March on in and ask one more time...Good Luck.