PayPal Holdings, Inc. Credit Card Complaint

PayPal Holdings, Inc. Credit card department,

Billing disputes Florida

I made my first purchase with Pay Pal -, 2015 and it was a promotional purchase. I 've asked to have my payment post on that purchase, but I learned they have n't been doing that until last month and now this month. The have me calling every month to put that money on that purchase and if I dont call they will place the payments somewhere else. Also I returned an item which they gave me credit for but they refuse to take it out of the promotional purchases and have it collecting interest. How am I going to pay interest in something I returned? I just made the call for this month and was told it was good for me to have the returned purchase still collecting interest. I dont know what else to do.