Roblox support taking weeks to reply, is that normal?

if it's a ban or a warning you're waiting on, skip the normal ticket. there's a violations and appeals section in the account settings that goes to a different queue, and that one's usually much quicker.

yeah unfortunately. outside of payment problems it's slow, and replying to your own ticket or opening a second one tends to push you back rather than forward. keep one ticket open, make sure the email on it matches the account, and put the username plus the date of whatever happened in the first message so they don't have to ask.