Thanks for your responses!
Well I'm now convinced it was an installer issue. For my own piece of mind I pulled out some boards that I had left over in the attic (the install was done almost 2 years ago). I took them inside, sat on the carpet and put a few together. I really didn't have a problem with any of the boards. Some of them were very slightly bowed but we're not talking bowed like bananas! Just very slight. SO, I'm thinking that the fact he didn't use tape coupled with the fact that he did a poor job of ensuring the floor was flat ( I assume a bumpy floor would also make for a difficult job) it's no wonder he had such a darn hard time!
Oh and I also did suggest to him that we should return the wood if it was such terrible quality and he said no he didn't think we needed to. In hindsight I think it's because he knew it wasn't that bad, he was just whining and perhaps exaggerating the problem.
Anyway, I'd like to use the same wood ultimately but I'm not planning to install for another 6 months or so, so I have a few months to really think about it!
Thanks again for your help!
Dee