Who's at fault for fat necrosis?

I am 6 months past ab lipo done by an OBGYN who Does lipo for years. For the last four months I have had hard lumps. Some came to the surface and exploded in infection. I just went to a PS who said that I need a tummy tuck to remove all the FAT NECROSIS that has developed from the lipo. Some of this necrosis is very painful when I lie on my stomach. The PS says these lumps are not lymph nodes and non cancerous, QUESTION Who’s fault is this? Lipo was very aggressive, I need an answer ASAP! Thank you!