It's a bit early to think about paying and given the covid situation it will be very difficult to get anyone to come out and would you want them in the house anyway? That aside there is some good advice here your problem like all problems needs more information before it can be addressed and the question of speed is paramount you might also like to tell us what you believe you are paying for i.e. what does your contract say with regard to the speed of your modem, is it for instance fibre optic or old fashioned copper, if fibre you should be looking at 100MBps+ depending on your contract for example mine is 1000MBps and a direct connection via an ethernet cable delivers in the high 900s wifi from the same modem through a Linksys Velop router delivers in the low 400s depending on time of day, number of active users and other factors.
In my experience HKT deliver the best service but you seem to have changed from them to another provider, your choice but all of the above still applies. It would also help to know which router you are using and the speed, some routers throttle the speed from the modem because they can't handle it.
Looks like there's plenty of help here now it is up to you to provide the information so that we can help you further.