Anyone know why I'm getting the faults after gearbox and torque converter

Take it back, let the repairer sort it

Just get some sort of idea as have spoke to them but saying could be the Tom but the tcm is showing as normal just ever other module can't communicate , possible broken wires or bad earth/live

Would be handy to know what the actual issues you are having are...

Problem is that not all the time but every so often then car seems underpowered the v8 rumble from exhaust becomes faint and the gearbox seems to hold gears longer e.g. Up to 4000rpm before changing up also mpg has gone from 25 to 18 ? Only fault that did show on dash was dsc warning stop happened twice both times when going round corner slightly faster than normal I know sounds stupid but one second the cars spot on puts you in your seat next gutless

Have just been told that faulty battery can cause these errors?