If immigration is giving rise to poverty, discrimination, poor housing and unemployment, should we not stop doing it like we're doing it at present?

Methinks you have it upside down. Immigrants are coming to Europe largely to get out of dire poverty, warzones and insecure environments (which to be fair is are often the result of the actions of European states and/or companies). Of course they come here poor (by European standards).

The thing that gives rise to poverty, discrimination, poor housing and unemployment is capitalism: if there is no market for providing people with decent food, clothing, education, housing and entertainment then it doesn't happen, and it doesn't. However, we have the physical means of feeding, clothing, housing, educating and entertaining everybody on the planet. To use the means of production and distribution for the purpose of meeting the needs of everybody, then everybody has to have a say in production. Democratise the economy, abolish classes, abolish money, every pub a parliament, the world for the workers.