SIAST has a first qualified, first admitted policy, which means that until you provide them with proof of all of the necessary pre-requisites, which include Standard First Aid and CPR-C, as well as some high school courses, they will not admit you to the program.
I have heard of them making a few exceptions and conditionally accepting people, with the condition being that they obtain their SFA and CPR by a particular date, but this is rarely done, as usually there is a wait list to get into the PCP program. I do not have the letter you received from SIAST in front of me so I can only speculate here, but I would imagine that if you did get an acceptance letter, as your post states, what you received was a conditional acceptance, which would have given you the opportunity to obtain the necessary pre-requisites by now.
This may seem a little bit blunt, but if you are serious about getting into the PCP program get off your butt and take your SFA and CPR-C already. It looks like you live in Saskatoon, and if that is the case, there are courses available EVERY weekend and at least once during every week as well (aside from during the holidays). Perhaps your posts on this forum are not an accurate representation of your English language skills, but based on what I have seen here, you are going to struggle with the written components of the PCP program. I would also be concerned about your reading/comprehension and I would suggest that you get your hands of the course materials and start looking through them ASAP to see if you are really ready for learning at this level.
The PCP course offered by SIAST is not a difficult program but it is certainly not a cake walk either. The instructors move at a quick pace and if you are not prepared going in you are likely to get left behind, and if that happens you will surely struggle with the exams. If you score less that 50%, even once, or if you get less than a 60% twice, you will be asked to leave the program.
I don't want to deter you from pursuing this if this is what you really want to do, but I want to ensure that you are going into the program with realistic expectations. The PCP program is a big jump from high school level learning and I have seen a lot of people struggle, and many fail, because they have had unrealistic expectations of the program.
And I would expect the comment regarding Writing 121 echos my comments about improving your English skills but I could be mistaken as I was not the OP of this comment.