Local Channels getting bleed over etc

Ok folks...can i get a little help....after spending several attempts on the phone with support...i got no help....

My local channels...always..from around 5pm till 10pm...have other stations trying to bleed over...and i get a CHANNEL NOT PURCHASED code...I have 3lnb oval...dish is set up correct..been working fine for the past few months...and now...grrrrrr....

So can anyone point me in a direction i have yet to travel..