Harassing Phone Calls

Since 11 November, I have had 7 calls from ***. Every time, the phone rings and rings until I answer it. Three seconds after answering the phone, the caller hangs up without saying a word.<br> <br> After a quick Google search, I found out that this number belongs to Edgars marketing. So I called in yesterday to ask them to stop calling me. The lady on the phone was very helpful and told me that she had removed me from the list of telephonic correspondence. And yet today, I once again received a phone call from this number, and once again they hung up on me before saying anything.<br> <br> What do I need to do to stop you from harassing me?