I would tell them to FUCK OFF INTO THE NIGHT !!!!!!
On a more serious note I would be seeing a solicitor to see who gave your details to a muppet security firm. DATA protection and all that !!!
Dont pay them I wouldn't, I would contact my MP get him/her to earn their money.
I would be asking how this firm got your details I would push that to the limit. I dont know if it is the same in England but the first visit to a solicitor here in Ireland is FREE!!!!!!!!!!!!!!
Go get them mate be aggressive dont let the bastards grind you down........
just a thought
