Poor Service and Communication

I have been getting calls from this company asking me to pay up my account. Sept 2021 I was given discount for my Zone Fitness account where I would be an amount of +- R350.00 per month for 3 months, the arrangement was accepted by myself and payment commenced from the end of Sep, Oct and Nov 2021. The lady that assisted me with the payment arrangement was Miss Laverene Cook and this was all on record. Recently, this past Saturday I received a call from Miss Phindiswa Dunga who asked me to make a payment towards the Zone Fitness account of roughly R400.00. On 02/02/2022 I received a call from lady by the name of Pearl, who explained to me that the Zone Fitness account was paid up and the R400.00 amount which I was being chased around was suppose to have been written off as I received a discount from the collection company. Today I received two sets of call from these guys asking to make payment towards the Zone Fitness account but to my understanding Pearl made mention that the account was paid up. I have also asked for the paid up letter via email this morning, provided them with all the details but it seems like they are still cutting down the tree so that they can send me this letter but strangely I am still getting the calls.