Synchrony Financial Credit Card Complaint

Synchrony Financial Credit card department,

New Jersey

I had a walmart/synchrony bank credit card.. always in good standing.. never late on any payment..i recently paid the account off 2 weeks ago in full.. my credit limit had been - today i received a letter stating Synchrony Bank was lowering my credit limit to - because of a credit score of - & derogatory collection of - from a medical bill ( paid in full by my insurance company ) ... they told me they do not have an appeals process and i need to contact transunion who is currently disputing the medical collection issue.. i was told by - my credit score was never - and in fact is currently over - ... i would like this information this bank is reporting to my credit to be corrected asap..as its really destroying a good customer and never gave them any issue in repayment.. i have closed this account down, however if it can be reopened at what my credit limit was.. i would be open for that as well.