Weil-Mclain Brrrr, cold and my Weil-Mclain oil burner, not old, is falling apart...as did the two prior ones Internet

Appromimately 5 years ago I had to replace a Weil -Mclain residential oil burner.  The failed burner was less than 10 years old and in order to get any warranty rebate, I had to replace the old one with the same brand, Weil-Mclain.  After replacement, I was not sent any refund.  Now the new, replacement burner is falling apart.  The walls of the combustion chamber fell in , disintegrated, and caused the burner to fail, the house to fill with black smoke, coating the downstairs with soot.  When I contacted Weil-Mclain, I was told that 'it happens'.  Both the installer last time, and the contractor who came today, have told me that Weil -Mclain is no longer a good product and I know that they do NOT stand behind their product.  An oil burner, properly serviced every year (mine has been serviced faithfully), should last longer than 5-7 years.  I have spent thousands of dollars on replacement and repair and I am cold!