Netflix + Max (Standard, Ad-free)--do the streamers credit. for the previous payment if already subscribed?

Hi, I got lost reading the website and past threads since Verizon seems to change bundles a lot.

Currently I have the Disney bundle through Verizon. I pay individually for Netflix standard and Max standard, Ad-free, total $35.

If I do the math correctly, getting the same thing through Verizon would be $31 per month (saving $4). That's the bundle with ads ($10) + Netflix standard without ads ($10) + MAX standard without ads ($11). Did I get that right?

My question is, what happens if I switch the Netflix and HBO halfway through their billing cycle? Do the streamers prorate me for the month before I changed since I'm now paying for the same account through Verizon?