just do tm47 with your current hotel at the time you report. Make sure they register your tm30 and ideally ask them to print the online stuff showing they did it for your
You must do it between 2 weeks before and 1 week after the 90 days, physically, at Bangkok immigration lak si. You need to get tm30 receipt from your owner, hopefully he registered you from the beginning. Another option is to leave the country and come back to reset the 90 days
the reason is simple if you mentioned dive master : you need a work permit for this as you will probably work for divers. No body cares but it’s illegal and most likely the embassy didn’t like it if you mentioned
1) you don’t need a visa for 60 days and extend for 30 days 2) the evisa for tourist gives you the same 60 days with extension not 90 days.
Probably they either cancelled the application because you provided a return ticket after 60 days, or they just considered that the visa is useless for you?
Anyway requesting for a visa is useless in your case