Hi paul,
Which type of balls (and what color) were you trying to buy? Can you go back to the item you attempted to purchase and post the URL for us? Just go to the item as if you were normally purchasing it and instead of clicking BUY NOW just right-click in your browser's address bar at the top and choose COPY. Start your reply to this post and right-click in the message window. Choose PASTE. If you could also post a screenshot of the error message you are seeing that would be tremendously helpful.
If you have 150 credits it should show up next to your name right above the PLAY NOW button on the left. It's possible you are looking at career earnings on your profile and that number signifies how much you've won, but doesn't change when you buy things in the pro shop. The figure above the PLAY NOW button is your active credit count.
On the CTTH accuracy award issue it has to be 5 consecutive shots in order to receive the award. There's been no reports of any issues with that award, so it's possible you just didn't get 5 in a row.
The putting meter will change to yards when you are on the fringe at St. Andrews. This is a known issue that we will be addressing soon.
Hope that answers your questions! =)