Called and left no message when I did not answer the phone

Tired of these automated telemarketers calling my cell phone. The number being on the DNC list is a joke at best. Telemarketing robo callers are one step below what you find in the bottom of a old outhouse.

i have been receiving calls once and twice a day from this place . if you call the number back you get a voice message that tells you press 2 to opt out from there call list when you do it then tells you they will take you off there call list and it will take 48 hours to do so . ok great you think ? well that was on tuesday it is now friday and i'm still geting calls the funny part is on thursday i got 3 calls from this place .
so today friday i call the number back to tell them in person to remove me from there last right after they called and i get a voice message stating they are sorry the promotion has ended . ok so why are they still calling me ?

I too received calls from this number.  I opted out and I now get a call from another number same service, and different location.  I just let it go to voicemail.

They called, nobody there, spouse hung up.  Caller id said "OCB"  Schweinhund.