Synchrony Bank Credit Card Complaint

Synchrony Bank Credit card department,

California

I opened a Stash Rewards credit card and set up my online account. I made a few purchases then - large purchase of around $2200.00 that was declined and set off a fraud alert on my account. I called Synchrony Bank to inquire why the transaction was declined and the told me I needed to send in identification verification to them in order to lift the hold from my account. They said it had to be mailed in and not sent by email. I mailed them the items they requested. Two weeks later I called them up to find out the status and was told they did receive my ID documents and still needed to review them. She said I would be informed of their decision in 7-10days. Three weeks have passed without a word from them. Today I received an email stating my payment is past due and to log into my account to make a payment. I attempted to do just that but I 'm still locked out of my account. I sent the documents they requested and still have no access to my credit line or the ability to make a payment. I need help resolving this matter with them.