Disgusted customer service

I went to see my doctor on 2nd September before i went i got authorization to see/visit my GP few days later i got an sms saying i have to pay my gp because the claim was unsuccessful! I have proof of the auth on sms , I've been calling the customer service line and all i get is that it's been send for reprocessing when my doctors assistant called she was advised the claim was rejected WHY I DON'T KNOW , this is totally unacceptable my doctor is demanding payment from me . can someone please fix this, this is terrible service , what's the use we pay? We are sick and still have to stress abour your agents not doing their job correctly . I'm now being advised the authorization they sent me on 2nd September was meant to be used on the 3rd! Absolutely nonsense! Because on the 3rd when i had to see the doctor again i got a new authorization code . CAN SOMEONE HELP THIS SERVICE IS PATHETIC