The Wages Protection & Contractors Liens Act Repeal Act 1987 states that a person or business repairing or improving goods this could include mechanic or a computer repair business is entitled to a lien over the repaired goods for payment of that work. In effect the lien gives the repairer the right to retain possession of the goods until the account is paid
For the repairer to enforce the lien they must have terms of trade clearly stating that full payment is due on completion of the work note a lien cannot be claimed against the goods if the repairers’ terms of trade are payment due by the 20th of the month following invoice.
If the repairer gives possession back to the owner and the owner leaves the repairers premises with the goods, the right of the lien ceases and the repairer has no rights to re-seize even if the account remains unpaid.
The act also states that a repairer can sell the goods by auction if the account has not been paid after two months of the repairer being in possession of the goods.There is a set process to be followed in regards to the selling of any goods and what happens to any surplus funds.
The lien does not need to be registered or be a signed document.
I recommend you seek advice from a debt collection company or lawyer to ensure you comply with the legal requirements.