B&D Scorpion Bit slow and may give you VWF temporatily with alll the vibration.
Slitting disk on a grinder. Fast, cleanish but will go through disks and is messy, noisy and a little dangerous.
Quality Hacksaw. Fine but hard on your arm and hand
The main reason I will be going ( eventualy ) for a flat pack is that I don't want to have to shell out lots for decent cutting equipment or risk injury on cheap stuff..
I have had a 9" Cutting disk break up at full speed and the grinder tried to make a jump for me..... And that's with precautions taken...
Go back to B&Q with it and ask if they can confirm that it is fit for your requirements, if not then they have potentialy put your safety at risk through improper product training. May be worth mentioning that fact to the store manager and see if they are a Caring Company
TT