Front Seat Belt problems of the 2003 Infiniti G35

Drivers side seat rocks on braking/turning. I had the car in for an oil change and asked about the seat. The dealer told me they replaced a part in the seat. It helps somewhat but there is still too much play in the drivers seat. It makes you wonder if the seat is actually secured to the car properly, and also in the event of a crash, would the seat hold up appropriately? also the brakes are squealing at 10,000 miles. Actually, they've been squealing for the last 4,000 miles. They are starting to make a grinding noise as well sometimes. I haven't been to the dealer about this yet, but it is a concern that the brakes could fail. I previuosly had an expedition and had problems with those brakes as well, but would normally get 20,000 to 25,000 miles out of them.

I am a 5'2" female and have a new G35 sport coupe. The seat belt sholder strap cuts into my neck do to the fact the starting point of the seat belt is too far back when I adjust my seat forward in order to reach the foot pedals. I have contacted the dealer and the consumer dept. At infinti and they say there is nothing they can do. If I were to be in an accident, this shoulder belt would surley cut into my neck and cause more harm than good. Please advise.