Upgrade problem Please help

I'm currently on a 4gb premium server, and i wanted to upgrade to a 6gb premium instead, so i paid ard $11 to upgrade, but it didn't upgrade, so i though the transaction didn't read through, so i paid again this time ard $24, which was weird, but i saw the due date to pay increase so thought the extra was justified. then the server didn't upgrade, but i have the invoices to show that i paid both $11 and $24 prices.(And how do i see transaction ID, is it inv number?)