MTN complaint over contract and faulty device

I'm truly disappointed with MTN; I've been using their services for years. I've never had an issue with devices or upgrades until now (apart from the constant spam calls, trying to sell me something I'm not interested in). My phone was ****** on the 23rd of December. I had to do a premature upgrade (2 months before expiry) on my SIM ONLY contract. I upgraded my contract to include a device, a Samsung S25 FE. I've never been penalized for upgrading prematurely before, because I was UPGRADING, not downgrading. I was paying R319/m, now R559. February debit order went off, R638 + R300,23. WHAT ON EARTH. My main issue is the phone and MTN's procedures. Does their 21 working day policy include public holidays? How can I have a device for a month, and it already has issues? How can I be required to hand my device in for who knows how long, and sit with no phone? Why am I being inconvenienced for a faulty Samsung phone that I purchased through MTN's services? I went into the Samsung store, and the technicians told me the phone is faulty. Why can't MTN log a return (for my device) with Samsung, and give me a replacement? I don't see why the customer has to be inconvenienced. I'm so tired of fighting.