4.4 rings

After having a "smoke problem" last fall "corrected" by a BMW dealer replacing the pvc under waranty, I am now told 11 months later that the rings need replacemtent for $7-$8K. Effect vs. cause?? My after waranty bmw repair shop (28 years going to them) stated that the 4.4 is known for ring problems. He called the head mechanic of the local BMW dealer who concurred. I was told by that BMW head service writer that you have to come in with a specific problem that they address under waranty but will not inform you of any other problems per their contract with BMW America. Any others out there with same problem? Last year I got rid of my 745 with the 4.4 which had to have the secondary pump air inlets unclogged for $5-6K. Same cause - rings.