Fault phone

Good morning, I am really not happy and very disappointed with the treatment I recieved from my service provider Telkom,I was directed to go to the Telkom shop, directed by mondo to take my device there,I bought a new device from mondo online after 9 days using a phone, the started to give me problem alot of problems they say I must take the phone to Telkom shop and I did just that they book the phone on the 9 of may 2023 and the phone was back on 31 may,I collected the phone on 01 June 2023,when I get home I realise the phone is still fault and it's even worse I took the phone back to the shop so that they can exchange it, they refused to so they say they must send it again on repair,the phone is new it's been less than a month using it,but they refused to exchange it, when I call Telkom they telling me mondo must help,but mondo is telling me about Telkom I'm stuck with the fault