This number has rung me 5 times today, when answered "whoever" hangs up. I put 141 then rang the number back, a message is heard saying "please wait trying to connect you". After a couple of minutes i put the phone down as nobody answered. Any ideas

~ Thread title edited by Dave

As you'll see from THIS LINK that is one of many numbers doing this.

It's cold calling really - normally cellphone retailers and, although calling back an 0870 number is foolish, it won't cost an arm and a leg (just whatever your calls provider charges [BT charges 7p/minute]) so ignore the "if you call it back you are calling a premium rate number" in Steve's second paragraph.

However, calling back any 070 number is likely to be very expensive - many are 50p/minute from a BT landline and heaven knows how much from a mobile.

Why do people spend their own money returning calls to numbers they don't recognsie?

I never return calls to 0870, 070, or 090 numbers, whether it's a missed call, and a message to call back a company I don't recognise, or have dealings with, because they cost.  It is most likely a company, in the case of 0870 or 0845, and in the case of 0871, 070, and 090, it's more likely to be a scammer, who deliberately wants you to call those numbers.

However, when I get a missed call from a mobile number (only 077, 078, 079), or a geographical number, I do tend to return the call (from my mobile's inclusive minutes) as there's every chance it could be a "person" trying to call, rather than a business, or scammer.

Also, returning calls to NGN numbers costs money (although I could use my O2 inclusive minutes) however there's no problem returning mobile, or geo number calls for free.

Remember, if they REALLY wanted you, they would wait for you to answer.
If you have caller id, you could save the number as "Do Not Answer"
I've got one who call me infrequently saved as "Tell Them To F*** Off".
As soon as it flashes up the parasite on the other end gets a right mouthful, and there is always someone on that number. (Just 'cause I'm called nice, doesn't mean I can't have a day off!)