Charging more

I bought a boost yesterday for a server shortly afterwards i looked at my paypal so I can see the bill. I have nitro so a boost costs around 3.50$ but I saw that I got charged 8.18$. I canceled my boost and if it charges it would make around 7$. I know that ain't a big amount of money but what if i bought 50 or 100 boosts that would charge me way more. I want discord staff members to try and fix their problem