Rennie, I use OZ blacks and OZ whites, I myself have never ad any troubles with them. Nor has anyone I have sold them to, if they did have trouble I wouldn't hesitate to replace them as I am confident with them.
Thanks, I'll try them again but OZ whites is one of the ones I bought before that never worked. The problem is that I rarely get the chance to go shopping (usually order online which adds the hassle of having to email, call or write then post the product back) and it looks a bit suspicious if you wait a month or 2 to return a bulb saying that it blew straight away when you installed it. I'd much rather if I could buy some that actually work first time.