I hope that the crew of CLX 794 had tea with no biscuits for basically level busting.The controller never instructed CLX794 to climb,the instruction was given to CLX 749.The controller misheard the callsign for whatever reason,but the CLX 794 crew took the wrong call as well.
As for sacking the controller for a mistake,well the ANSP obviously has no idea about human factors.Some would agrue that 700ft and 3 miles is a technical loss,but isn't that why TCAS was developed as a last line of defence.
So what was the background noise levels in the OPS room?
In the last places I worked in there has been full scale arguments,a £5 kettle at 100db used by management,ATSA meeting chatting gallery,and a sing along with plonker ATCO,all drowning out the R/T and that is with the latest headsets.You have to use very plain words to remind these idiots it's an OPS room.