I was on an hour before start time 2:30 PM AEDT.
I asked for raid invite 10 minutes before raid time but did not get raid invite, and so I asked again 10 minutes later.
You should always find out who is running the raid and send him a tell rather than asking in guild many times. This is much more likely to get a response - remember raid leading is a very very busy job.
There were past methods we had to manage this that have probably fallen by the wayside - they arose from having to manage too many guild members - rather than managing alts. But you need to get in touch with the raid leader - you should be able to ask any officer thats on on the night who the raid leader is - you can find that out through the guild tool.
As a side note - I would in the past have gone into manage guild raids and been able to fix this kind of thing - but for some reason that functionality no longer exists - Art or Jowdii may have some idea how to do that now.