you can also buy directly from the wholesaler, www.frankiematernity.com. If you ever lose the little brush for cleaning the tube, you can just buy the little brush from the wholesaler directly as I think this is the only place you can just buy the brush alone.
You can also buy Dr Browns from Bumps and Babes in Peddar Building, Peddar Street.
I strongly recommend Dr Browns if you are having problems burping your baby. My two babies had a lot of "wind" when I used pigeon, Avent etc but the situation improved so much when I changed to Dr Browns. The nipple is so much softer - I could tell my bbs were drinking much more comfortably. Before that, the milk would spill out from their mouths all over their clothes, mouth and bibs etc whilst they were drinking but now, that does not happen anymore.
Of course, Dr Browns require more work to clean etc and are more expensive but I think they are definitely worth it.
there is not much difference between the two shapes - it depends on which type of nipple your baby is used to. If the baby likes Avent type, then go for the wide neck but if like mine, they were used to Pigeon type, then go for the narrow neck.
But you can check Frankie Maternity website for more professional information