I need only 1 certificate. Limit increase request rejected

I have a static site hosted on S3 and I need it to be https. So naturally I went to Certificate Manager and tried to request new a certificate but got error and was told to contact support. I created Limit Increase Request ticket to be able to have 1 certificate in Certificate Manager and got rejected. Support wasn't able to provide me an explanation why exactly I was rejected in such tiny limit increase request. My AWS account is not too young, I am already using it for more than 2 years. Any advice on how to get my request accepted?