I'm having extremely similar issues atm. I had no heat for a month or so, then my heater core went out. Dealer changed it and has not been able to fix my heat after 6 visits. They are putting fault on my thermastat right now for the no heat issue, but haven't said anything about the coolant leak.
As far as my coolant leak it first happened after my heater core went. They changed a hose on plastic piece going through firewall. A few days later I still had a leak, and it ended up being that plastic part that went through the firewall. At the same time I had a sensor go out (engine coolant sensor?). The dealer paid for that plastic piece and labor, then paid for labor on the sensor. I paid for the sensor and had it changed. After contacting VWoA, they are reimbursing me for the sensor, as I should have never been charged.
To my current situation. My heat still doesn't work, and I still have a coolant leak. The other two times it was a complete loss. I would immediately leak any coolant put into the car. This time it's a very slow leak. It'll take about a week for all the coolant to disappear. I have let the car sit over the weekend, but did not notice any coolant anywhere.
VWoA is going to see if they will cover my thermastat, since the dealer says that will fix my no heat issue. I don't think it will, but if they cover it, then no biggie. As far as the leak here again, they did not say anything.
If VWoA doesn't cover it, then I requested another dealer diagnos my car to confirm it is the thermastat that will fix all my issues. I will not go to my current dealer again if I have to pay anything out of pocket. I do not trust them anymore if I have to open my wallet.
If I'm having the same issue and it is my water pump, then that isn't covered under the emissions warranty is it? I'll keep an eye on my water pump to see if I can see anything leaking.