Poor Service

I'm a member of GEMS (unfortunately not by choice). I am on the Emerald Value Option which means I need to have a Primary and a Secondary Nominated GP(s) for consultations and specialist referrals. My Primary Nominated GP passed away so I asked GEMS to remove him and replace him with another GP. They decided to keep the deceased one and remove my secondary GP who I was consulting and who had referred me to a specialist around the same time, now they do not want to pay the full amount because they are claiming that I only nominated my GP on a date later than the consultation date meaning a co-payment must apply because I was not referred by a nominated GP. I have called them after every 7 working days for about close to 6/7 weeks now but the situation remains unresolved and the service providers are charging me for the accounts that remain requiring an upfront payment. Its common practice to have to wait for weeks for them to resolve the tiniest issues.