In contentious business, a legal practitioner shall not charge any amount in respect of legal costs expressed as a percentage or proportion of any damages (or other moneys) that may become payable to his or her client or purport to set out the legal costs to be charged to a junior counsel as a specified percentage or proportion of the legal costs paid to a senior counsel. A legal practitioner shall not without the prior written agreement of his or her client deduct or appropriate any amount in respect of legal costs from the amount of any damages or moneys that become payable to the client in respect of legal services that the legal practitioner provided to the client.