Unfair billing from Singles50

On September I subscribed with Single50 but I wasn't happy with it then I unsuscribe it after paying them for 1 month. On Saturday 22nd of December 2018 I received an email from their loyers saying that I must pay R1, 161 before the 28 of December 2018.I emailed them and tell them that I have unscribed with single50 but they say I have resucribe of which is not true if you subscribe with them they send you pictures of which I never received. I asked them to cancel my name on their website and they said I must pay them first it is very unfair these people are stilling money from vonerable people. Please help me I don't have money to pay give these people. Regards Christina