Who I have the same questioned this topic

I originally had the $50 Unlimited plan selected on my prepaid service. Well I could only afford the $35 refill card (realized that's all I needed anyways). I had a balance of $0.05 on my account (leftover from the $10 free airtime when I purchased the device). So I bought the $35 refill card, added it. Giving me a balance of $35.05. Well I had sent a text message before remembering I had opted for the $50 plan, thus going to My Verizon on my phone and changing my plan from the $50 to the $35. My balance before I changed plans, and after the text was $34.85. However, my account activity log showed a "Bundle Renewal" at the same time I added the refill card. So why is it every time I send a text message, my balance continues to drop? The plan shows it has Unlimited Messaging so why is it charging me?