Your MP gained the right to represent your constituency by receiving more votes than any of the other candidates at the last general election or by-election. Once elected, the job of an MP is to represent the people of his or her constituency (constituents) in Parliament, whether or not they voted for him or her.
You only have one MP so even if you voted for one of the other candidates and you disagree with the views of your MP’s party, your MP is still there to help you with all matters for which Parliament or central government is responsible.