How do I stop/block a repeated pain-in-the-butt caller on my mobile?

[boomster]

Hi, I'm not being lazy here, I've searched everywhere that I can think including the maker's 'help' web page.
Okay, my mobile is a basic Nokia1800, Virgin, being the provider. My problem is constant calls every day without fail, from a finance loan company saying I owe them money and will take firm action if nothings done to clear my debts. This is, of course, total, utter crap. I have never returned a single call and just 'delete' any message that leave in text format.
Suggestions from wifey and a few friends inc., telling the police, change my number, get a new sim card. I do not want to do any of these 3 things unless I've no other choice.
Anyone out there think know a tried and trusted solution that I might implement to eliminate my ongoing pain and frustration?
Either way, I thank in advance. all of you kind folk for reading this, even if you have no advice to pass on to me. :)

[David H]

I had this a few times, but eventually they found the name of the person they wanted and changed it from mine. Assuming it's not your debt then the good news is if they're using your mobile number they haven't a clue who you are. Have they mentioned your name? (don't tell them if they ask).

Basically if they have just got the wrong number there's nothing you need to do to your phone as it would be like selling your house if they were bothering you there. Get their company name and address, and call their head office and tell them they've been calling your number and you will be contacting a lawyer if they do not stop (no need to but it makes them wake up). It often takes a good few attempts to be removed from a database but the main thing is they're only a nuisance and once you've spoken to their boss should ignore everything afterwards, except to call back in a few weeks if it carries on and could (which is free) make a complaint to trading standards. Either they wrote down the wrong number or were given a false one deliberately but either way it's not your problem and don't put yourself out changing phones.

[Bigeye74]

Change number, yours appears on at least one database that you don't have access to. It will be less hassle

[VHG]

Ring Virgin and tell them to block that number.

[boomster]

Thank you David, I'll implement your sound advice asap. :)
Thanks, too, BigEye74 and VHG. :)