Slow draining toilets and gurgling, help please

[endo55]

Hello, would greatly appreciate some pointers

Toilet downstairs drains slowly. First floor toilet causes bath to reflux water and make noise. Second floor toilet causes shower to gurgle.

Tried Mr Muscle drain unblocker almost everywhere. Tried plunging the toilets, shower and bath. Tried a high pressure water injector device (13894) on the toilets (but not the bath)

Any ideas what else I can try? Any other tools I need?

Cheers

 

[ShaunCorbs]

Sounds blocked in the underground part need a drain cleaning company with a camera to check and see where it is

 

[endo55]

Sounds blocked in the underground part need a drain cleaning company with a camera to check and see where it is

Thanks, what's a reasonable cost for this?