If you are in pain, and the nhs wait is ridiculous (72 weeks! ) and have already had all the scans, and can afford the treatment privately, I would go ahead. However if a phone consultation is not right for you, or you would struggle to communicate this way, then ask for a face to face appointment.
The charge is presumably not just for the phone call, but for the specialist to look at your scans, gather information, and then organise any other examinations or tests needed.
Remote consultations can work quite well in some specialities, ( although not when language or hearing well are an issue) - a lot deciding on next steps in diagnosis or treatment is from asking the right questions, listening to symptoms and gathering information from test results.