Refusal to pay claims

We are seriously disappointed in this scheme. Every single claim - which is not many, proofs to be a challenge to get paid. I have just contacted the scheme again to enquire why the PMB claim was rejected and after being given a telephonic explanation which I know to be incorrect I have requested that the scheme put the reason for nonpayment for me in writing. Instead the agent insisted on sending me the treatment plan for my condition and put the phone down on me when insisting that I want from the scheme in writing the reason for nonpayment.