I wonder whether the raspberry you grew as Glen Ample was wrongly labelled. This is not uncommon. It is easy to make mistakes when looking after a lot of plants. If you don't like the fruit I would recommend planting something else. Have a look at these profiles for other summer fruiting varieties:
I wonder whether you have club root in your soil. This will cause stunted growth like you describe. If you dig up the plants you will see that the roots are swollen and distorted. There are no chemicals available to gardeners to treat club root, but adding lime to the soil helps, if you cannot move your brassicas to a different area.