Who called from 6105712734

From Bath Pa. shows as sixtel LLC....didnt leave message

From Bath Pa. shows as Sixtel LLC....didnt leave message.

calls a private unlisted number (mine) then hangs up

CALLED five times today so far..says unknown number on caller id ..calls but no message  left

I have received 15 calls from this number in 7 hours, no machine, no person when I tried to answer a few times.  I called from a different phone and it is the electric power supplier "OFFERING A DISCOUNT"
I have already asked them to take off their F list several times in the past and they keep calling, when I am able to get an answer from their machine it says to press 2 to be taken off their call list --- IT DOES NOT HAPPEN.