Michael: I hadn't realised Qcad is open source! So I can open it fine in Qcad, but when I save it as "R13 DXF Drawing (Teigha)" it's still not right.
(It's much better than before though.)
James: It was designed in Illustrator, which I don't have. Good trick about importing pdf. I'll try this too!
If anyone can fix this in two mins, please do. If it's likely to take you longer, then leave it but please send some other suggestions if you have.
I'll keep trying the two options above. Many thanks guys!
Tasos