I dont know exactly how the rotation works but this offer disappeared for me too then later in the day it came back. I used the code that the website gave me instead of the code in the description and I still got my diamonds. The code the website gave me actually gave me a few more dollars off my order too!
Yeah. Other games I play that have battle passes, once all main rewards are earned we still get rewards every time we level up. Its usually just game currency but its something. I see no reason why we couldn't have something like that here. Stars or diamonds when we reach a certain amount of points.
Idk what customer support you contacted but you have to contact TapJoys customer service. Go to the offer you completed and scroll down you'll see the red bar. Sometimes they take a couple of days to respond.
I wasn't feeling the kollection either. Idk what they were thinking with that headphone crown combo. But I did spin once to see if I'd be lucky enough to get the kstars. I ended up with the energy. I wont be spinning that kollection anymore tho.