You can check the charges on the website of the State Knowledge Bureau.
Also, your annual fee of 90 yuan must have been reduced, usually for three years. Remember to pay the full amount from the fourth year, unless you issue a certificate of fee reduction then.
In addition, if it is convenient for you, you can go to the local patent agency to pay the fee yourself, and you will know when you ask. You can also pay by bank remittance, which is very convenient if you use online banking.