Bad treatment by Gems

I'm not happy by the attitude of consultants at gems the way they treat us. I have been trying to call gems from April 2015 till now and it is my sixth call I made with gems regarding a pathology query and I have to wait for 20 minutes on the phone without the consultant not coming back to me and when I try to explain to a consultants all of them are rude to me. I don't know where to report especially when you don't get an assistance from gems. Really gems is treating me badly.