It doesn't have to be your operator's fault, there may be other problems on your end, with your equipment for instance. If you are not satisfied after having looked at our Self help section and followed the instructions there, it is probably a good idea to call your operator.
Be polite, to the point and describe all the actions you've taken so far. Then you will probably get faster and better help.
If you are in Sweden and do not feel satisfied after a couple of calls to your operator, you could try to contact Telekområdgivarna to proceed. They can, if it's worth it, give you tips on how you could take the matter further to the National Board for consumer complaints (ARN).