Money deduction after cancelation of services

In January I received a call from Discovery Vitality selling me their product which I took. A week later I replayed to the emay they used when they were sending me the certificate to I cancel with them because I was told that I will not get the 3 months probation period that they normally offer to test their product and services.

Last month April I realized that my salary is R1527 short, I then checked my payslip only to find that they did a payslip deduction for the previous 3 months.. I then contacted them to return my money and they told me that they did not get my cancelation email and that they can only cancel in April but another deduction of R509 as I will be serving my cancelation notice.

Can Discovery Vitality please pay back my money because I didn't even use their service or product for that matter so what am I being charged for

I need my R2036 back please.