Pirtek (Ipswich) Pty Ltd

I asked for a 1/4 npt fitting and was supplied a 1/4 bsp fitting instead and the guy claimed it will fit fine. I googled to find out they have a different thread pitch and would cross tread if used together. The guy tells me to just force it in and it's not dodgy because he's been doing it for 26 years. I'll never go there again if that's the advice they give and the level of their workmanship.