Poor istore online returns/exchange services

I bought an item from istore online and the item was delivered extremely fast. However, I realised I ordered the wrong item and sent an emailing through the istore enquiry platform requesting the item to be returned and exchanged. This request was on 30/03/2022. Istore responded on 31/03/2022 stating that a collection can be arranged and a credit amount will be given with a deduction of 20% handling fee. On the 31/03/2022 I responded with my address for collection and again on 05/03/2022 when I had no confirmation regarding the collection. Only on 08/04/2022 did istore online respond to say that they will send someone to collect the item. After not hearing back from them regarding the credit amount, I emailed on the 20th and 25th of April. On the 25th they finally rep**** stating they would send me a voucher by the end of the day. On the 29th I had still not received the voucher, and sent another email asking for a response which they have still not responded to (it’s the 6 of May). I called istore customer service on 3 May to make a complaint and ask them to resolve the issue. The gentleman kindly apologised and stated that the voucher would be emailed by the end of the day. I have still not received it. This process has taken 36 days and has still lot been concluded! I have never received such poor online, returns/exchange services before. I would not recommend buying anything from istore online unless you are absolutely sure that it does not need to be returned/exchanged/refunded.