[Closed] Wrong size frame - What are my options?

I bought a Canyon Roadlite about 2 month back in a medium flavour. I'm 6 foot, but according to their online framesize finder thingy, this is the right size.

But, I'm just not getting on with it. After an hour or two in the saddle I'm in quite a lot of discomfort. Not numb, just discomfort.

At first I attributed this to a new saddle and told myself to man up. Then it never got any better, so I got another saddle, which didn't really make any difference. Tinkered with the saddle position and I found that if I moved it all the way back it kind of helped.

If I stay at the front of the saddle, it does help, but I'm constantly having to pull myself forward, naturally I want my arse to be further back, which leads me to believe the frame size is wrong.

So I was just wondering, what are my options to try and alleviate this problem? (preferably beside a new expensive frame 🙁 )