Poor service

I went to Midas Robertson to buy inner and outer CV joints for my car. I explained to them what vehicle I was driving and they gave me the wrong sizes. When changing it on my vehicle I noticed that the inner CV joint was the wrong size. When I returned it to get the right size they gave extreme attitude and claimed that they wouldn't take it back cause the box was opened. The manager was rude and had a attitude. I had to spend more money because they didn't know the sizes. Poor service, I'll never make use of them again