Being Abroad But Being Called for Military Service

​Hi everyone, I’m 21 this year and currently in Canada. I’m having some issues with my paperwork right now, so I’m no longer in school, but I’m still residing in Canada and waiting for my citizenship via marriage.

​Just recently, my family back home in Vietnam told me I received a military service summons. Previously, I went in for the medical exam after receiving the notice and was granted a two-year deferment because I was studying here. Now, after two years, they’re calling me again.

​Does anyone know if there's any way for me to get another deferment or bypass the requirements? Thanks in advance for any helps!