psa grading service switched my sports cards for others Newport Beach CA

I have a relatively large sports card collection (approx. 5,000 cards) that I have been collecting since the late 60's. For the last year and a half I have been sorting my cards and educating myself on card values. I took 2 of my cards that I intended to have graded by PSA to various card shows to find out if what I believed the card grades to be was reasonable. The concensus was that an 8 or 8.5 per card seemed right.                                                                                                                                                                     Nothing to yell out "I won the lottery" but good enough to get a few bucks if sold. After my cards were graded by PSA I looked online and saw that the cards had a grade of 5 and 6 respectively. After receiving the cards I knew immediately that they weren't the same cards sent in.                                                                                                                                                                                                                                                               For one thing, I have 3 of one of the cards that I sent in and 4 of the other. Of the 7 not all were worth sending in. But the others were very similar in condition basically a toss-up of which to submit. One of the cards returned to me had three minor but noticeable creases on 3 of the corners.                                                                                                                                                                                                                                                It also had a print defect on the front and centering on back tapered from approx. 15% to about 60% from one side of the card to the other. A definite grade of 5 but not my card! I 100% believe that PSA switches out higher end for lower end. Maybe high end dealers haven't seen this to be true because rare cards would be very hard to switch due to limited numbers.                                                                                                                                                                                                                                                             Hence, they don't get cheated. I understand that a class action suit may be looked at. That would be great. Doesn't PSA realize that if that were to happen, when the plastic holders are opened the owners DNA wouldn't be on the card because it's not their card?