I have not had as bad an experience with cannabis as yours, but have had trouble with the available strains over the past few years. This has led to a major decline in my intake of it, and I'm currently not even using any.

The current production of Sativas that are grown to be extremely strong is the problem. There is an artificial effect of these super-strains that many of the younger people here do not recognize as abnormal, because they likely never had the older, naturally-grown stuff that we had in the 60's through about ten or fifteen years ago. The vast majority of it was imported, and felt much better to use. If you wanted to get really stoned, safely, you could do it safely by smoking a few joints - but often just one was more than enough.

The future for me, and others, is to learn to grow some Indica - if I can find the correct seeds.

If you're not happy with the stuff you've had, vote with your wallet and don't buy anymore.