Ruining lives

My accounts have been paid up, I have no judgements, defaults, no accounts in arrears. All my current accounts are up to date and yet my score keeps dropping. It is currently on 519, I cant get through to query this. The line goes quiet when Im transferred. I have been trying to work on my credit standing and Im worse off now then when I actually had debts. What does one need to do to get a healthy score?