I had been with an MNC for nearly 10 years. At the time when i join i was a logistic executive after 2 years later i was require to handle administration, human resources, properties etc which was not given any transfer letter and i just continue to do, then after few years later i was being requested to do sales coordinator job which i did but my previous responsibilities still being carried on eg part of the administration works and there wasn't any transfer letter or job descriptions given.
Can i refuse to take any jobs not related to my current job which is a sales coordinator?
You must be pretty good in your work and that's why they keep heaping you with more and more work. Don't be shy to ask for more pay and other benefits if you think you still can shoulder more work. If they do want to give you any consideration, then you will reasons to refuse to take on more jobs.
The problem here is the mgmt is taking advantages, as for myself i don't mind to take on more responsibilities but i am not rewarded with any consideration and lately the last 3 years i didn't have any increment. They are still other coordinators in the company and why aren't they also doing the same to them. When i try to tell them that i would like to just concentrate on my current field that is sales coordinator which had alot of things to learn and do too but they say no choice i still have to carry on with the previous duties.