This is normal when an RG is broken, Tom. Don't worry, nothing is disappearing from your account. St Andrews CTTH 110185 was the first RG I saw that was broken. Then Merion 110181, Koele CTTH 110162, Celtic Manor CTTH 110236, Pinehurst 110285. Your Set of the Week too now. There are probably more.
When one breaks, the system keeps trying to settle it every few minutes, then eventually every hour. These settlements can get in the way of others settling, causing a domino effect. Eventually, if left unattended, the whole lot will stop settling correctly. It is NOT something CS should be leaving for 15 days!!!
Every time WGT tries to settle a broken RG you were in, your game client balance will get a message to add the credits to your displayed balance. Anything that causes the balance to be refreshed will then reset the credits to what they were before because the tournament is broken, hasn't settled properly, so you don't really have the credits yet. If you notice your balance when this happens, it will look like it has gone down. But you haven't lost any credits, and you will eventually get the payout you deserve when WGT gets their act together and settles the RG(s) manually.
Feel free to copy and paste this to CS. The longer they leave it, the longer it will take for them to sort out and the more RGs will become unavailable to us while we are stuck in the old ones that won't settle.