Unable to do upgrade on Mobile contract

I've been trying in-vain to do an upgrade on this mobile contract of mine ( ********** 228) with your company, firstly your stores (Westgate and Cresta) don't have the advertised device Samsung J7 Prime in Black and secondly your Sales department numbers 10213 and 081128 are inundated with calls that I gave up on holding for them after 10-15 min on atleast 3 occasions. Mine is such a simple transaction, I only want to upgrade/ renew my contract, should I rather cancel the contract and move to Vodacom? I only want the Black J7 Prime, no other device will do. I really can't understand why your company have't done anything about your bad service after all the bad reviews you get on a daily basis, on all teh social media platforms.