I'm mid way through a dental procedure. My (NHS) dentist talked me through the process, explained the risks attached, gave me his opinion illustrated by x-ray pictures then gave me time to think. As we're in stage one there is a temporary covering, I am instructed to return immediately if it detaches before the next appointment. I was also told the expected life of the finished article and it was made clear if it failed it would be replaced. All highly professional. In your situation think I would be asking for remedial work at no charge and perhaps querying the suitability of the filling as this is a recurrent problem. Better to take action than get cross about it, the worst they can say is 'no'. Hope it works out for you, it's upsetting as well as frustrating.