What are the speeds you're currently paying for?

If your ISP cap you at a certain amount then there's not much you can do. IF you promised speeds up to 200Mb or whatever you can use a network cable. If thats out of the question then you can get a repeater and a gigabit wifi usb adapter. But that might not increase speeds greatly since you're adding in more points. you could try upgrading the NIC card.
Keep an eye out for driver updates for your pc, if you're behind on driver updates this can sometimes cause issues with connectivity.

Don't forget that there are people in your area too, the bandwith for that particular is always going to be leeched, even by devices within your house. If you have 3 members in a family, each member will have a phone and a laptop, so there will be a lot of leeching going on. Not enough to make a huge difference to your speed but at peak times (5pm) you will notice differences.

So in short, use a cable.