I had that problem with CPP. I placed an order online and they emailed me to say I needed to call due to an issue with it. I spent a total of 5 hours on hold over 3 days before someone finally answered the phone. The problem was that I used a dedicated card number with only the amount of the total authorized and they were adding an extra $5 "handling fee" that wasn't listed on the order confirmation so it wouldn't go through.
Got that sorted with some angry words and threats of a lawsuit if they pulled that **** again. After 3 weeks, I spent another couple hours on hold to see where my parts were because I never got a shipping notification. They insisted that my parts were indeed shipped and I should get them any day.
A week later, the parts did show up with a label showing that they shipped 2 days *after* I called and asked about it.
When I opened the box, they had sent me chromed parts instead of the black I had ordered. After *another* round of being on hold, they told me to just paint them and they would credit me $3 for the paint.
I finally just said screw it, did a chargeback on the CC, and refuse to do business with them ever again.
I know a lot of people swear by them and have good experiences with them. In my case, they had a whole stack of opportunities to make this right and squandered every one of them.