Refund from Gems

Good day I'm having a problem with Gems. On the 10 September I deposited an amount of R7822 this amount was meant cover for three months since I'm a pensioner. They told me they going refund me an amount of R4525 then I received a letter with a date 18 January and they letter required me to fill it in with the correct bank details since my bank account details are incorrect . I sent them all the required documents on the 12 of February and since then I have been calling them and all they say is they did refund me on the 9 of February in the account number that was closed since 2019 so when I go to the bank they say it's impossible cause the account is closed in 2019 the money will bounce back. They telling me me they refunded me R2400 on the 9 of February when I call them they keep telling me to come with a bank statement of the closed account and that is impossible . They never reply to the emails always making excuses. So I want to know between Nedbank and gems where is the problem.