Refusing to pay me back my refund

On the 27/02/2022 I made a eft of R2903 by mistake instead of R290 to my late Grandmothers account, been paying this account for the past 2 years. I called Dstv explained what had happened, i was requested to email proof of payment, bank statement nd my id, i emailed all those documents. I called dstv to find out when will my refund be processed, Firstly i spoke to Thabo Mosia who assured me that it will be processed before the end business. 4 hours later i get an email requesting that Late Granny who passed on 10 years ago should write a letter to them requesting for my money to be moved to my dstv account. When i called them i spoke to a lady who started being rude and asked me alot of questions requesting serial no of the decoder, smart card no mind you i kept telling her that i stay in gauteng and those things she wants are in north west, that time i am using my airtime.. I got an email saying since my Granny is late i need an executor letter for that person to agree to move this money from my grannies account to mine, i do not have that letter now i am being told that i can not be refunded there is nothing they can do. These people only wants to recieve money but fails to return my hard earned money that i eft by mistake.. I have a premium account with them, now i have to follow them just to refund my money... I have proof of payment and statements but that is not proof enough to them. I keep wondering what if i had made an eft to a wrong account, was i going to be declined to be refunded? I am so disappointed with this company, no acknowledgement of documents that you requested. Its an honest mistake that happened, i want my refund