In July l started the process of getting a crown.The dentist drilled and filled the tooth and fitted me with a temporary crown.A few days later my tooth became infected and they told me l needed a root canal.The dentist billed me for the crown and I've just received a bill for the root canal.Should l be responsible for the cost of the root canal?l thought that the dentist would be responsible because the tooth became infected after he had drilled and filled.

Your tooth got infected because it just did..the dentist was treating the current problem & trying to protect it by putting a crown (like a band-aid) on the tooth & protecting it. Obviously he could not see though the tooth to see that the nerve was infected & dying (no one can without expensive scans!) so then he properly did the root canal to treat that problem. In any case u would need the crown.so now u r done, & problem is solved.
The drilling & filling is what was fixing a problem..that the tooth continued to have problems is not his 'fault'! It is ur tooth, & it sounds like it was on a downward spiral. Now it is fixed.

FYI,
it is your tooth and IF the dentist began and started the root cabal then you are responsible for paying it.
YOU ALWAYS HAVE THE CHOICE OF PULLING THE TOOTH, but most do not want this.
The dentist did not cause the infection, but w/o the RC this tooth will ultimately need extraction