Q. I've seen some leaflets advertising essay-writing services. Is it OK to use these for my assignments?
Any assignment that you submit must be all your own work (unless you have been told you can work with others on a group assignment).
Allowing someone else to write your assignment, or to work with you to produce it, is a serious academic offence and subject to a range of penalties.
Buying your assignment from either a commercial service or someone you know, is a very serious offence and will be treated as fraud.
If you haven't done the work yourself, then you haven't learned. Would you want to be treated by a healthcare professional, or your children to be taught by a teacher, who had paid someone to do their degree for them?