Personally, before I agreed to the $99, I'd do one of two things. First, you can sign up for the Warranty they offer for $5.99 a month. After your problem is fixed by a tech, you can then cancel. Secondly, and what I'd try, is insist they send another unit to you. Get advanced tech support on the line and tell them everything you've tried, including the swap of the sat in ports. As an installer myself, tech support should realize that if the problem didn't follow, then it is not the lnbf, cables, ground blocker (assuming there is one); it is the box itself. Whole lot quicker & cheaper (on them as well as they'd have to pay a tech just to swap the box) on everyone. And, there's a good chance the field tech may not have a spare 522 on the truck when they pull up, so you're still waiting.
Hell, if you have to, tell them a relative brought over their 522 and everything worked just fine with their unit hooked up to your cabling.
Note that I'm basing all this on the fact that they problem "didn't" follow when you swapped the cables.