Woohoo!! Finally got my "C" person on board. Took forever (2 months) to get him to set everything up and connect his Serve acct (which I use.). Then after all was said in donw, there was an error with claiming received money and he told me to just log in and do it. It was using the same password that I knew from other stuff so I could have just done this myself two months ago!
Ugh! Anyways, he got a weird error. He was able to send money ($1k) with an Amex GC but when it was time to claim money, it said that he had to add a credit card (almost like his acct wasn't verified). I guess Amex GC isn't sufficient enough in that aspect. He didn't want to add any real bank or credit card to this but luckily I was able to get past it by adding his Serve card as a real credit card.
Now I can do A->B->C->A!