Pathetic feedback on emails and telephone calls

Have been struggling with them to pay doctor's accounts since 13 June 2017. They made an error on capturing the authorisation date (thus the payment was done from savings not from benefits - ie. authorisation number supp****). Since then we have resubmitted account, sent emails to ********** called 4 times already to follow up and NOTHING. Today I asked to speak to a supervisor - was put on hold for 13 minutes... I eventually ended the call. This is absolutely shocking, that there is no feedback. I am desperate to actually speak to someone that can resolve this issue.