I suggest that you go to another cosmetic dentist and see if they will start with bonding plastic instead of bonding veneers. Eventually you may have veneers done but maybe its down the road. Bonding can look great and is a great option to begin-especially because the cost is less...
If there is no infection in your tooth and it is simply calcified, you will probably be fine without a root canal. If the tooth is cosmetically unacceptable, then a single veneer should be a possibility. Make sure you find a good cosmetic dentist who has the ability to correctly...
Since you have had four veneers placed and only the area above one is giving you grief, it is obviously a localized problem. Obviously you need to go back to the dentist who placed the veneer and resolve the gum problem. The veneer could have been placed to close to the bone abd the gum will not...