Hi. I had the rear suspension replaced with many other components changed on my Nissan Xtrail '08 model. The mechanic was unable to realign the wheels properly afterwards. I had another garage try and they couldn't adjust it properly albeit they managed another slight adjustment. They don't know why it's not realigning. I can feel it when driving. Mechanic said its probably the new parts I bought on Ebay. Company said its not. Other garage said arms look okay. Any advice? Is it just new parts on an old car? What should I do? Thanks. 

I wonder if you should take it to another garage - one that specialises in four wheel alignment

The suspension should always first be adjusted from the rear (if there is adjustment possible) otherwise I can't see what the issue is (accident damage aside)