We were away for one week and I saw this number on the  missed calls at least once, sometimes twice a day while we were gone but there were no messages on the answering machine.

I have had the same experience as all above.
Let them pay for the call when the answering machine picks up - maybe they will quit calling when their phone bill runs up.
A reverse search, however, says it is a cell phone so maybe they have an unlimited call service most likely. If so, their employees are only wasting the company's time and money.

They just want to sell you a vacation package, but it's always a scam and you never get the vacation.

These people call and hang up 2 times a day

Yup, multiple times over the last 2 months or so -- silence then automated GoodBye.  These folks need to get a life and get the heck out of mine... !!!