Is anyone else having issues with the S9, with constant call drop outs. Have had mine since its release on Optus. I have researched this, and know that samsung released this model, knowing it had this problem, so i know its not the optus network, as i can use my other older mobile,also on the optus network, and dont have this issue, I read some people are up to there 4th and 5th replacement handset and still have this issue and how samsung keep releasing useless software updates that do not rectify this. In other countries , class action suits against samsung have been happening, i can only hope one is raised here in australia. I am payimg for a S9 that is useless and only good as a paper weight.
We don't really need class actions as Australia has very good consumer protections. A product must be fit for purpose. Both the manufacturer and seller of a product are liable for its functionality. Optus may suggest you deal with Samsung direct but they can't offload their statutory responsibilities (Not suggesting they are trying to btw).
If its a major issue (and this sounds like one) then its your choice on a refund, repair or replacement. I'd probably go the refund. you're also entitled to any forseeable associated costs, so that would include any plan you signed up for as part of buying the product. I would suggest requesting the plan be retained but the phone be replaced by another handset model. However it may be simplest just to return the phone for a full refund and start again from scratch in getting a new phone.