If you haven't done anything different in between those five times I think it makes sense that you're not doing any better. I'd recommend that you get into a study group online or in-person get a tutor do something different.
You don't need to have a massive increase as a part-time applicant but I think that a 28% Quant might limit your chances especially because you don't have a quant oriented job and you have a C+ in finance.
Your main task here is to prove to them that you're not going to flounder in the course work and I think that you should put that up front and center in terms of your priorities.
That could be you actually taking some classes at a quality University in accounting and stats or whatever.
Simplest way would be to do MBA math which is an online self-paced program that sends the transcript to the school. If you can get through MBA Mass I think they would be more confident that you could get through the courses. It takes about 12 to 20 hours. (I talk about this class so much on gmatclub youd think that I'm getting a spiff from them or something.)
Do you have any grades from undergrad that speak to your quant abilities? You did major CIS so I'm wondering if maybe you did some calculus, some advanced math?
I think I will say do MBA math and just start there. If you get that done they will know that you are okay to take their classes. If that is a struggle then you really need to focus on getting a tutor and getting this handled. Because there would be reason to be concerned that you could fall behind.
That said I don't want to put too much emphasis on this it's kind of a limiting factor but you'll still need to put together a really good showing on the application of course. I would hire professional to work with on this.
https://MBAPrepCoach.com