Change my Visa

Only an employer can apply for an employment pass or a professional pass - so you are not really in a position to change it. You would need to ask a new employer to make the application for you. That would mean cancelling your current pass first.

Singapore is a different country so none of the immigration status you have in Malaysia is valid there. Depending on your nationality, you would also need a tourist type visa to enter the country.

Dear Sir,
Gravitas is Correct and let me add more.Your Pass under Plantation Sector means you can only work in plantations only.Since you are a Chef in a Restaurant,it will be an offence and misuse of your pass.You can be arrested,Deported and jailed or fined.So forget about changing pass as your name will reflect in the Immigration as a General Worker( Unskilled) so they will not give you a higher pass( Professional Visa).So do not believe anyone who says this can be done.
You also cannot change employer in malaysia under your current visa unless you check out of malaysia and come down under another employer.

You either go to work in singapore and that is a different application with the Singapore manpower agency via your employers there.

Regards,
Vanisa

Sadly, I think the Agent is the one at fault for exploiting your skills and misdirecting your services. You are welcome to advise who the agent is.