Appaulling and Poor Service

Since the router has been exchanged, I am experiencing poor quality and connectivity issues on a daily basis. Also, please explain what does 2Ghz next to my Wifi name means. I tried to get hold of your technician with no success. His number that I was communicating with him when he came to exchange the router is ***. There is also another Wifi on my name called (5Ghz) which also I do not know what is this for. I am not sure how far now I should take this matter because everytime I ask to contact Vumatel directly, l am told that I can't. I am working from home and this is such an inconvenience and I need to pay for such a pathetic service.