Iphone Store Trade-In ****

Their Tv add says proudly "Your new iPhone contract shouldn't cost you more than your old contract" but it is a ****. For that to happen you have to trade-in your old iphone. I have a 18 month iPhone X(in perfect working order and in mint condition) that the Apple iStore website will give me R8000 as a trade-in. When atempting to trade it in, they first did a "diagnostic check" in which my phone's speaker failed - even though it works perfectly. The R8000 trade-in value suddenly fell to R3200 - in other words R4800 for an iPhone speaker (23% of the totaql cost of the phone new!!!!)