Sending a letter to IRCC main office may not be effective, unless you are requesting for urgent processing and if they are going to approve that request, based on their reasoning. I think the issue is, as someone mentioned on the forum yesterday, everything depends on the agent working on your file, and unless he/she gets that urgent request from IRCC main office, the processing time will take its own time. I sent a webform asking if they can speed up the process, because I am travelling multiple times in November and December. They responded by asking me to apply for urgent processing, but none of my reasons are valid, so I never went through with it.