Right...we were being pestered by these calls at all hours of the day. Many were "caller withheld" nuisances. I even had one call me after midnight. So, about 3 weeks ago I spent the best £39 I have ever spent in ages and bought us a BT 8500 . You must have "caller display" to get the best out of it. You can buy them from Argos, I got ours from BT which took a few days for delivery.
Since setting it up , calls from the Swansea people are blocked as are all International/ caller witheld numbers/ anybody who is not prepared to state who they are, etc.
Genuine callers will state who they are. Nuisances hang up once they are asked to state who they are. You won't know that they are ringing you when that is happening. Only family and friends+ any outside agency whom we consider are essential numbers, such as our GP for instance, are stored in the phone. We accept their calls instantly.
It's amazing going through the day and not having to hear these nuisances ringing us all the time. I usually check the caller list before going to bed which shows the list of all incoming calls+ those that have been blocked.
Now, I appreciate that many people consider it an inconvenience to have to pay for a new phone + many don't like paying for "caller display," but for a couple of quid extra a month, I personally consider it's money well spent.
Google BT 8500. There's loads of information on there to read about the phone.I promise if you buy one, you will get peace at last.
One last thing, don't worry if you are a technophobe; this piece of kit is so easy to set up. Even the owner's manual is easy to follow. Good luck, whatever you intend to do.