Synchrony Financial Credit Card Complaint

Synchrony Financial Credit card department,

Alaska

I purchased a - with a no interest promotion through Synchrony bank -/-/-. My regular payment is $160.00. I made $200.00 payments on -/-/-, -/-/-, -/-/-, -/-/-, and -/-/-. I was just told I can not pay ahead. I have to make a payment once a month before the - of the month. I also can not set it up for autopay. They want me to physically go in and pay it because if I miss it, they go back and charge me interest on the ENTIRE AMOUNT from day -! There is also no grace period days. Something is SERIOUSLY wrong with this company being able to get away with that. The entire time I 've been thinking I 'm a month ahead!