Poor service and feedback

Numerous calls have been made to them and their management but no success on a repair to vehicle, I've repaired it out of my own pocket and they still refuse to pay out the money's spent on repairs.<br> I've taken the vehicle to telesure assessment centre in century city and felt they've miscalculated the incident so taken the vehicle to 2 different approved panel beaters and both their quotes were of similar figures, also have offered to take the vehicle to BMW warranty approved repairer but was told it's not necessary,I've appealed they reassess the repairs and have been put on hold since, they don't respond to my emails and their management use SMS to communicate only to keep you on hold by saying they're still busy assessing or they have a system fault but never get back to you.<br> What can be done to correct this issue?