You have several elected representatives at different levels of government.
Your 3 Lisvane and Thornhill councillors represent you on Cardiff Council. The Unitary Authority is responsible for all aspects of local services and policy, including planning, transport, roads (except trunk roads and motorways), public rights of way, education, social services and libraries. Most councillors are not paid a salary, but get a basic allowance for the work they do.
Your Cardiff North MS represents you in the Senedd. The Senedd has a wide range of powers over areas including economic development, transport, finance, local government, health, housing and the Welsh Language.
4 South Wales Central Senedd region MSs also represent you.
Your Cardiff North MP represents you in the House of Commons. The House of Commons is responsible for making laws in the UK and for overall scrutiny of all aspects of government.
Lords are not elected by you, but they still get to vote in Parliament just like your MP. You may want to write to a Lord (more info).