Why don't I get a call back from support, after asking for limit increase?

I'm currently in the process of migrating my software from a local server to the AWS cloud. It's an image search engine, and we use deep learning models to infer image embeddings. The embeddings are stored in memory (~50GB), and the inference is performed on a GPU. For our resource requirements, we needed a single EC2 g4ad.4xlarge instance, and I submitted a support ticket to increase the G limit of my account. However, it was not permitted initially since the support suggested contacting sales using the call back feature to describe my use case. However, I've now tried on two different days to get in touch with sales through the call-back feature, and no one ever called me back. Is the call-back feature currently down, or do I have to wait a few days to get the call?

We have already migrated our data (nearly 2 TB) to an EBS volume, so we pay daily for this volume and cannot utilize the data without the EC2 instance -- which is why I need a quick resolution for this issue.

Thank you.