Nationstar mortgage mortgage company "Fix loan / monthly payments keep going up" Lewisville, Texas

Nationstar is keep increasing my monthly payments even though we have a so call fix loan of 6.25% and I have tried several time to have my interest rate decreased and they tell me  we do't make enough money.
we're  on a fix income at present and and our son is living in the house going to college. We stay their several time a month. We need a bank we can trust , If we can pay $1,941 a month at 6.25% I am  sure we can pay 2 to 3% interest rate. We feel that Nationstar trying to make us default on our loan and they can take our home. We need help and we need it now. If we pay one day after the 16 of the month we have to pay $69,00 more and the. They are the worst mortgage company I have ever did business with . robor calls 2-3 time a day 24/7 and Holidays. We are been treated unfair by this mortgage comp.
 We want to join a class action ASAP/ put our name on your list.