RSC - CTM ....nightmare closing account

Trying to close my CTM / RCS account is a total nightmare . Settled account on the 11/02/2021 and then received another email 15/02/2021 with another settle amount . Called the customer service department and was highly irritated that the agent did not understand what was happening . She refered me to a supervisor who then advise that the account will take 36 days to get closed . I think this is utterly ridiculous as I do not see the reason why it cant be closed immediately or within a few days after payment is received . I'm also closing accounts with other retail groups which will be closed with 3-5 working days . Quick to open the account but slow to close ????????