My employer wants me to sign a contract that doesn't reflect my role and responsibilities. Indeed the responsibilities I have don't reflect in my current grade/pay. I have undertaken such responsibilities for 2 yrs now. What do I do?

Do you mean that the contract would have you responsible to do things differently than you are doing them now?

Revise the contract so that it accurately reflects what you do and offer that to your employer. Or if the employer really wants you to do things differently, and you don't want to, find another job.

You need to discuss if these are you new duties or if you will need a new contract.

You better have a good discusion about this matter with your employer.and find a central point which is reflect your responsibilities but also meet your employer needs