Wider brackets for fitting bottle cage

[glaw5]

Might be a stupid question this so please go easy if it is!

I've bought a bottle cage to fit to my mountain bike but have found the tube on my frame is too thick for the plastic bracket. Does anyone know of any tips for how I could fit it or where I might be able to buy wider brackets?

Thanks!

 

[PpPete]

Maybe a wire cage rather than the moulded plastic type would be better ? Or longer bolts ?