Regarding a porcelain crown......?

Is it common practice for a dentist to drill through a porcelain crown? My dentist did not do a good enough job (6 months later I was still in constant pain) on my root canal and he had to re-access the space. Instead of removing the crown, he drilled through it, completed the root canal and then filled the drilled hole. The filling is now chipping out and it looks awful. Is this common practice? The crown was expensive and I feel like I should have gotten a new crown or he should have removed the first one prior to correcting the root canal.

--------------------------------------------------------------------------------------------------------------------------------

Additional Details

Dani: "Crowns are not cheap so the dentist will not just give you a new one for free when drilling through the crown". I am not concerned with the cost to him. I paid for a beautiful crown and when it was determined that his work was insufficient, he drilled through the crown that I paid him $1,500.00 for. Now I have a filling (I paid for a crown, not a filling) that is chipping out. That's my concern.

--------------------------------------------------------------------------------------------------------------------------------

Dr. Albert: Do you mean if the permanent filling material is chipping? The dentist's office is trying to charge me to "fix" the filling (they are the only dentist involved in all of my work) and I'm absolutely certain that they will want a replacement crown paid for in full. Thank you for your response!