Very bad service and of no value to anyone.

I cancelled my membership in December 2019. To date QVC won't accept the cancellation. They say that I have to pay for the rest of my life. This is a membership program by cancelling i am putting the other members at a disadvantage. This is absurd, I have not used this scheme since 2015. I have paid in R296000, I entered into this membership in 2005 and basically got nothing in return. Now they have threatened to black list me for the outstanding b of R34000. What legal right do they have to hold one to this membership? How can I report them for this unfair treatment. I am 70 years of age, a pensioner and only get a pension of R4000 per month. Could someone give me feed back.