Are you asking whether legally, pet plan have to pay for this treatment?
If you say that you’re not happy to put the animal through another operation so soon after the neutering one, I don’t know what kind of resolution you’re looking for.
Whoever broke the tooth has been negligent and is responsible for doing or paying for the remedial work. As you chose the vet, the contract is between you and the vet albeit that the insurance were paying the bill.
If Pet plan will not pay for this, and the vet will not pay the Bill, then you are faced with getting the work done yourself and then either suing the vet in negligence for the cost of the remedial work or making a complaint to Pet Plan and if Pet Plan will still not pay up, then making a formal complaint to the Financial Ombudsman Service.
Can I clarify anything for you?
Please rate the service positive.
The thread remains open for further exchanges.