I am expecting to get my temporary work visa in the next couple of weeks, but the "sponsoring" company has just told me that the number of hours I'll be working is a lot less than I had thought. So much so that without extra work on the side, I won't be able to do it. Is it possible to do other part-time work with this type of visa?

I know I'll get a SIN number, which would indicate I might be able to work elsewhere as well, but I have read that the visa is for one job only, and if you want to change jobs, you need to apply again. Is this right?

Thanks for your help.

No you can't and yes the visa is only for one job. Sorry!