I want my seat to be slightly higher, is there anyway i can buy a thicker seat or build the existing one up a bit?

Strip the covering and foam off the old one, stick new thicker foam on the seat base, shape it and recover.

Might not be much help, but a lot of the racers here bolt/weld/hoseclip a piece of 12x12mm box section steel on the subframe where the seat rests.

You can still get the bolt through the tank and use zip ties around the lugs on the back of the seat to secure it.

I ran mine like that in the first year before I put on the tyga bodywork.