Poor service delivery

Jumia is an online store associated with ZANDO as as I have shopped on ZANDO before I felt I could trust this shop and get good service so I ordered a set of Avent bottles in the beginning of July 2020,the order arrived 3 weeks later and it was not what I ordered I logged a return and was assisted by Samatha who told me that she cannot process the return as the order had not been marked as delivered on their side,but she said she would follow it up.The order was eventually updated to delivered weeks later,I have since sent countless emails with no response trying to get my refund with no response and their call centre is not working at the moment