Synchrony Financial Credit Card Complaint

Synchrony Financial Credit card department,

Credit line increase/decrease Pennsylvania

I have a Walmart credit card with a $500.00 dollar limit. I have always paid my bill on time. In -/-/2016 they lowered my limit down to $400.00 dollars without any notice. I thought it was fraud on my account because I did not receive a lettering in the mail, no email not even a phone call. So, I contacted Walmart that 's how i found out my limit was lowered. I ask if they can notify me if this happens again. They did it again in -/-/2016. lowered my limit without notice. I was in the store in line paying for my item and my card rejected. I felt so humiliated when my card declined, i had my children with me. I called Walmart and they lowered my limit again without any notice. I never gave Walmart auth. to check my credit report. My credit report has not changed since I had this card. So this is why i am confused as to why they keep lowering my limits without notice. This is also leaving a negative rating on my credit report. I have never paid late on this card. I an not understanding how this can be legal. I am trying to get a loan for starting a new business and this is negatively affecting my credit. Please help!