First late delivery, then wrong phone, now awful service

So a salesperson called me on Valentines day making me an offer for a Samsung Grand Prime Plus. I tell him I am not interested in that phone but would consider a Galaxy A6+ which meant by the way if I take the contract I'm changing from my old service provider for the first time since 2003. He then sells me an A6+ and takes all my details, etc. telling me the phone would be delivered in 3 to 4 working days. By day 5 nothing happens so I email them and ask what's going on. They say it has only been pre-approved but the delivery data hasn't been sent to the courier yet. After a week's struggle DSV finally gets the data and makes arrangements to deliver my phone. Yesterday I get the phone... but it's a Grand Prime NOT the A6+ I ordered. Seeing as I can't reach their call centers without having a MTN number I have to work through email again. After HOURS of no response, I get a response telling me to go to a MTN shop to sort it out. I go to the nearest shop to me that is open after my work hours just to find out they can't do anything there as they're not a "direct shop" I must go to one of the other shops which might I just add are all in the busiest parts of the city. This morning I go before work after 8am - just to find it only opens at 9am (same time as I have to be at work). I email again and they responds HOURS later asking for an account number or something because they can't find my ID on the system. I sent the account details and I'm STILL waiting for a response or call or something. I'm fed up. And let's bet they will charge me for Feb even though I don't have a phone yet - can't wait for that fight. Very tempted to just cancel everything and search for a cheaper option with better service!