MMR LP ..?

plz help me understand m I blind here? MY win rate is over 60% . Won 7/10 of my placements …? I finished bronze i went to look on>OP.OG I went from A MMR-silver to bronze to iron in 3 games and had a 10 game win streak and my LP is w13/L23 and was placed in iron 5 And well i message riot and they say Its because im lower MMR in my bracket ,I cant get any lower WTF my stats show other I get some Jibber Jabber from riot saying to win more IT clearly makes no sence!