Ranked Boarder and Banner

Dear Riot, I am here to inquire about the banner and boarder on my league of legends account. Last season i obtained the rank of Platinum 5, However when i load into game i have the board equivalent to Silver 1. Last season i did obtain a rank of Silver 1 in both Twisted treeline and Ranked 5v5 Flex. All of this being said i have seen on other accounts the banner that they have is either Gold or Platinum yet there Ranked Flex is one Tier down. If someone from riot could please get back to me i would greatly appreciate it thank you.