In the big scheme of things, $700 is a very low credit limit. With good enough credit (and the discipline to not spend money just because you can), it's not unreasonable to have multiple cards each with limits in the $10k - $30k range.

With that in mind, the advice of "put your spending on a card" and "keep your credit utilization low" isn't as contradictory as it seems. You can get a few cards, build up $75k - $100k in available credit, and easily put a month's spending on them without pushing your utilization above 5%.

It's very likely you were not offered $100k, but you were offered a quantity of shares valued at $100k at the time of the offer.

That's important: you weren't promised dollars, you were promised shares.

You're still getting the shares you were promised, so there's nothing for you to have recourse against. The deal hasn't changed.