Manner of objection

There's no much difference between the both sir... you can file either rectification request or grievance in respect of the wrong demand. the only difference is that, in case of rectification request, it needs to be disposed, within 6 months from the end of month during which rectification request is made

Who is responsible for rectification ? Will CPC themselves do it and will send a corrected intimation u/a 143(1) or I have to do something in pursuance of my rectification requests acknowledged by CPC and informing meas such assigning a reference number?

If the latter option is the proper way of resolving the matter, then what is it?

Yes cpc will do rectification and send the rectification order. reference number is for future communication in respect of the rectification request made by you