Stop deducting my money

They came to my workplace, **** and said the will is for free .. next thing there's R300 going out on my payslip and apparently i was going to have to pay that money for the rest of my life. Now i have been cancelling this contract with them since june. They are telling me it only got cancelled in September and there'll be 2 more deductions on my payslip before it stops deducting.... I mean im a single mother raising a child with special needs, maybe to them 300 is nothing but to me, its a lot... They should have just explained to me in detail and told me the truth that im going to pay.... Stop lying to people, giving them free pens yet you are opportinists.