Nokia 6 broken 2nd time still under warranty now my problem

I went to the cell c store yesterday to get my phone that i send in for repairs a month ago. I live in the ceder-burg mountains so the nearest store is 210km away from me. When i got to the store the phone was never repaired. instead send in for a quotation. My phone is 6 months old and i feel it was supposed to be repaired for free since it is under warranty. So when i asked them what is the problem with the phone they said the charger port is corroded. For a 6 month old phone that should not happen. I have been on a contract with cell c since 2008. for more than 10 years i have been a loyal customer and i have more than 1 contract line. This will be my last year as a cell c customers as i have a strong feeling of canceling both contracts as cell c dont give an f for their customers. I am so angry. when nokia came out i was so happy. renewed both my contracts with a nokia 6. one started freezing a lot but that happens. 8 monthes later the other one froze and just died. i took it in for repairs and it was an lot of effort to book in. 2 months later cell c contacts me and say ok you can get a new phone. i get new phone. 6 month later i have same problem now they tell me sorry. sorry is not working for me. what are you going to do. i feel like canceling my contracts wih immediate effect and to stop my debit orders