Apple One iCloud Storage Account Different from Media Account

Very confused here. I have an iCloud account and also an account for iTunes. With my iCloud account, I've purchased 200GB (I have 193GB used now). I went to purchase Apple One Individual, expecting the 50GB to be added to my 200 GB of storage. But it doesn't work that way. The additional 50GB with Apple One is assigned to the iTunes account. I went to move it to the iCloud account and the 50GB replaced my 200GB making me short on storage. I went back and re-purchased the 200GB on my iCloud account and the 50GB is reassigned to the iTunes account. Very confusing and disappointing. How do I get that 50 GB assigned to my iCloud account without it replaced my existing 200GB. HELP!!!